PTEN and colorectal cancer: Mutations, loss of copy number, epigenetic silencing and downregulation of PTEN protein by miRNA can result in PTEN function inactivation, leading to activation of PI3K/AKT/mTOR pathway, which subsequently increases tumor growth, invasion and metastasis across a diverse set of solid tumors including breast, endometrial, prostate, renal cell, hepatocellular, glioblastoma and colorectal cancers [5, 6].