ABCG2 and colonic neoplasm: Similarly, Lin et al. showed that the suppression of the PI3K/AKT pathway leads to the downregulation of cyclin D1, Bcl-2, and ABCG2 expression, while it increases the expression of p21 and Bax, which collectively are attributed to the re-sensitization of 5-FU-resistant HCT-8 colon cancer cells [32].