CASP3 and colorectal carcinoma: In addition, we measured cleaved caspase-3, a biomarker for apoptosis by Western blotting (WB) and enzyme-linked immunosorbent assay (ELISA) in CRC cells and found that SN38 in combination PEV induced increased levels of cleaved caspase-3 (Supplementary Data Fig. 1b, c), indicating that the combination not only enhances growth inhibition but also apoptotic cell killing.