PARP1 and colorectal cancer: The detection of PARP-1 and caspase-3 cleavage by western blot analysis, identified the apoptotic mechanism which is involved in the reduction of RKO after inhibition of autophagy (Fig 2B). Taking all the above into consideration, it can be proposed that autophagy has a cytoprotective role in colorectal cancer cell line RKO, since inhibition of autophagy with 3-Methyladenine was remarkably correlated with decrease in cell viability and appearance of apoptosis.