CASP3 and colorectal carcinoma: We used the tumor conditioned medium (TCM) from human CRC cell line HT29 cells to mimic tumor microenvironment, and examined its effect on the proliferation and apoptosis of VSMCs in vitro. Our findings suggested that human CRC cells induced VSMC apoptosis in an exocrine manner throuth activating the caspase-3 via mitochondrial apoptotic pathway.