Cyclo[Phe-Tyr-Lys(iPr)-D-Arg-2-Nal-Gly-D-Glu]-Lys(iPr)-NH2

LY2510924 specifically blocks SDF-1 binding to CXCR4 with IC₅₀ value of 0.079 nM, and inhibits SDF-1–induced GTP binding with K_b value of 0.38 nM. In human lymphoma U937 cells expressing endogenous CXCR4, LY2510924 inhibits SDF-1–induced cell migration with IC₅₀ value of 0.26 nM and inhibits SDF-1/CXCR4-mediated intracellular signaling. LY2510924 exhibits a concentration-dependent inhibition of SDF-1–stimulated phospho-ERK and phospho-Akt in tumor cells. Biochemical and cellular analyses reveals that LY2510924 has no apparent agonist activity^[1]. LY2510924 chiefly inhibits the proliferation of AML cells with little induction of cell death and reduces protection against chemotherapy by stromal cells^[2].