CASP3 and colorectal carcinoma: Finally, in two representative CRC-SCs treated with either oxaliplatin, irinotecan or 5-FU, given alone or in combination with UCN-01, we show that the cytotoxicity induced by UCN-01 combined or not with irinotecan is mediated by activation of caspase 3 in CRC-SC line #1.1, as assessed by the decrease of the full-length caspase 3 (procaspase 3) and of its downstream target Poly-(ADP-ribose) polymerase (PARP) (Figure 2D).