SM-164 is a potent cell-permeable and bivalent Smac mimetic which bind to a XIAP protein and binds to cIAP-1 and cIAP-2 proteins. It is developed as an anticancer agent. It plays its antitumor roles through inducing degradation of cellular inhibitor of apoptosis protein (cIAP)-1/2, antagonizing X-linked inhibitor of apoptosis protein (XIAP) and inducing TNFα–dependent apoptosis in tumor cells. SM-164 is a bivalent mimetic containing two SM-122 analogues. It binds to cIAP-1 protein containing bothBIR2 and BIR3 domains, cIAP-2 BIR3 protein and XIAP protein containing both BIR2 and BIR3 domains. References: Kocab AJ, Veloso A, Paulsen MT, Ljungman M, Duckett CS. Effects of physiological and synthetic IAP antagonism on c-IAP-dependent signaling. Oncogene. 2015 Oct;34(43):5472-81. doi: 10.1038/onc.2015.3. Epub 2015 Feb 9. PubMed PMID: 25659587; PubMed Central PMCID: PMC4530109.