CASP3 and neoplasm: Consistent with these results, IHC analysis of endpoint tumor xenografts indicated that metformin significantly induced lower Ki-67 (a marker of cell proliferation) and higher cleaved caspase-3 (a marker of apoptosis) protein levels in FLO-1-shCtrl than FL-1-shAXL tumors (P < 0.001, Figures 8C–E).