PTEN and breast cancer: Additionally, elevated Bcl-2 transcription has been observed in certain drug-resistant breast cancer cells expressing activated Raf-1.37 Activated CREB can regulate Bcl-2 expression, and the interplay between Akt, CREB, and Bcl-2 is implicated in the development of drug resistance.38 We discovered that overexpressing PTEN and p53 genes can improve the oxaliplatin sensitivity of SW480 cells and notably, PTEN has more impact than p53 because it directly inhibits the PI3/AKT pathway.