Cell experiment:

The human GBM cells (i.e., U87MG, U343MG, or ANGM-CSS) or the respective GSCs are seeded and incubated for the indicated times with the indicated concentrations of SA16 (1 nM to 100 μM), MP7 (2.5 nM, 25 nM, 250 nM and 2.5 μM), or Alisertib. When indicated, cells are treated with MP7 and Alisertib in combination. To verify GSC chemoresistance, U87MG or GSCs are incubated with 50 μM TMZ for 72 h. For the long-term treatment of cells, NSC or complete medium containing drugs is replaced every 3 days. Cell proliferation is determined using the MTS assay: the dehydrogenase activity in active mitochondria reduces MTS to the soluble formazan product, whose absorbance at 490 nm is measured with an automated plate reader. The mean background from each test condition is subtracted, and the data are expressed as the percentage of untreated cells (control). IC50 values are derived from the sigmoid dose-response curve. The percentage of inhibition is calculated as 100% minus the percentage of cell proliferation[1].

PDK1 inhibitor is an potent and selective inhibitor of PDK1 with potential as anticancer agent. GSK 2334470,a inhibitor of PDK1, has IC50 value of 0.00251µM and CHEMBL1172241 with IC50 value of 0.085µM. [1]
PDPK1 stands for 3-phosphoinositide-dependent protein kinase 1, which is crucial for the activation of AKT/PKB and many other AGC kinases including PKC, S6K, SGK. [2]An important role for PDPK1 is in the signalling pathways activated by several growth factors and hormones including insulin signaling. PDPK1 functions downstream of PI3K through PDPK1's interaction with membrane phospholipids.[3]PI3K indirectly regulates PDPK1 by phosphorylating phosphatidylinositols which in turn generates phosphatidylinositol (3,4)-bisphosphate and phosphatidylinositol (3,4,5)-trisphosphate. [4]However, PDPK1 is believed to be constitutively active and does not always require phosphatidylinositols for its activities. Phosphatidylinositols are only required for the activation at the membrane of some substrates including AKT. PDPK1 however does not require membrane lipid binding for the efficient phosphorylation of most of its substrates in the cytosol.PDK1 is implicated in the development and progression of melanomas.[5]Many cancer-driving mutations induce activation of PDK1 targets including Akt, S6K (p70 ribosomalS6 kinase) and SGK (serum- and glucocorticoid-induced protein kinase).   
GSK2334470 is more effective at inhibiting PDK1 substrates that are activated in the cytosol rather than at the plasma membrane. Consistent with this, GSK2334470 inhibited Akt activation in knock-in embryonic stem cells expressing a mutant of PDK1 that is unable to interact with phosphoinositides more potently than in wild-type cells by Immunoblotting.[6]GSK2334470 also suppressed T-loop phosphorylation and activation of RSK2 (p90 ribosomal S6 kinase 2), another PDK1 target activated by the ERK(extracellular-signal-regulated kinase) pathway.[7] GSK2334470 will be useful in probing biological processes controlled by PDK1. Therefore, GSK2334470 is much more specific than other reported PDK1 inhibitors.
Reference:
1.MurphyST. et al. Discovery of novel, potent, and selective inhibitors of 3-phosphoinositide-dependent kinase (PDK1).  J Med Chem. 2011, 54(24):8490-500.
2.Mora A, Komander D, van Aalten DM, Alessi DR. "PDK1, the master regulator of AGC kinase signal transduction". Semin. Cell Dev. Biol. 2004,15 (2): 161-70.
3.Vanhaesebroeck B, Alessi DR. "The PI3K-PDK1 connection: more than just a road to PKB". Biochem. J. 2000, 346 (3): 561-76.
4.Frödin M, Antal TL. Et al. "A phosphoserine/threonine-binding pocket in AGC kinases and PDK1 mediates activation by hydrophobic motif phosphorylation". EMBO J. 2002, 21 (20): 5396-407.
5.Scortegagna, M.. et al. "Genetic inactivation or pharmacological inhibition of Pdk1 delays development and inhibits metastasis of BrafV600E::Pten-/- melanoma". Oncogene.2013.
6.Ayaz NAJAFOV. Characterization of GSK2334470, a novel and highly specific inhibitor of PDK1. Biochem. J. (2011) 433, 357-369 .
7.Tamguney, T. et al. Analysis of 3-phosphoinositide-dependent kinase-1 signaling and function in ES cells. Cell ,2008, 314, 2299–2312.