Ganglioside GD1a is a sialic acid-containing glycosphingolipid found in brain, erythrocytes, bone marrow, testis, spleen, and liver. [1] It can be shed from the surface of tumor cells into the microenvironment where it influences tumor-host cell interactions to promote tumor cell proliferation, invasion, and metastasis. Ganglioside GD1a (20 μM) also increases endothelial cell proliferation. Furthermore, ganglioside GD1a has been shown to act as a functional coreceptor for toll-like receptor 2 (TLR2), enabling the recruitment of TLR2 to lipid rafts when bound by a bacterial toxin.[2] Ganglioside GD1a mixture contains ganglioside GD1a molecular species with C18:1 and C20:1 sphingoid backbones.

Reference:
[1]. Mukherjee, P., Faber, A.C., Shelton, L.M., et al. Thematic review series: Sphingolipids. Ganglioside GM3 suppresses the proangiogenic effects of vascular endothelial growth factor and ganglioside GD1a. J. Lipid Res. 49(5), 929-938 (2008).
[2]. Liang, S., Wang, M., Tapping, R.I., et al. Ganglioside GD1a is an essential coreceptor for Toll-like receptor 2 signaling in response to the B subunit of type IIb enterotoxin. J. Biol. Chem. 282(10), 7532-7542 (2007).