AFP and hepatocellular carcinoma: It was also found that intracellular AFP was involved in the regulation of the PI3K/AKT signaling pathway during research on the drug resistance of HCC patients to all-trans retinoic acid (ATRA) via direct interaction with phosphatase and tensin homolog (PTEN) and competitive binding to the retinoic acid receptor β (RAR-β) which resulted in suppression of the PTEN gene and the enhancement of cell growth [85,86].