PTEN and malignant colon neoplasm: GM3, a ganglioside, treatment dramatically increases cyclin-dependent kinase (CDK) inhibitor (CKI) p21WAF1 expression through the accumulation of the p53 protein by the PTEN-mediated inhibition of PI3-K-Akt-MDM2 survival signaling in HCT116 colon cancer cells [29].