PTEN and colorectal cancer: Cell cycle arrest, abnormal expression of apoptosis-related proteins (increased P21, P53, Fas and Bax; decreased the Bcl-2), tumor suppressor genes (PTEN and P53 up-regulation) is often found in cancer cell lines [20, 25, 36, 41, 43, 45] (MDA-MB-231 and MCF-7 breast cancer cells, ML-1 and ONCO-DG1 thyroid carcinoma cells, DLD-1 colorectal cancer cells and U251 glioma cells) with increased apoptosis.