PTEN and cancer: A potential link of PTEN expression on CRC development and progression was noticed in this study which showed nearly 80% of patients with lost PTEN activity was stage IV CRC, while, no one of patients with strong PTEN activity was stage IV, and nearly 26% of patients with strong PTEN activity was stage I CRC.; with higher PTEN expression levels found in patients with early-stages CRC (AJCC stages I&II) and lower expression levels or even negative PTEN staining found in patients with advanced stages of cancer (AJCC stag III& IV).