HSPA1A and neoplasm: The substituted imidazole derivative 2a (Figure 1, apoptozole) was discovered as a pro-apoptotic inhibitor of Hsc70 (KD = 210 nM) and Hsp72 (KD = 140 nM) in 2008, which showed high tumor cell growth inhibitory activities with GI50 values in the nanomolar concentration range (GI50 = 220 nM for SK-OV-3, 250 nM for HCT-15, and 130 nM for A549 cells) [37].