E2F1 and pancreatic ductal adenocarcinoma: PI3K was reported to induce SKP2 expression via mTORC244 and further investigations revealed that this regulation was mediated by E2F1-promoted SKP2 transcription in pancreatic ductal adenocarcinoma cells.45 Similarly, we found that inhibition of PI3K resulted in decreased binding of E2F1 to the promoter region of SKP2 and reduced expression of SKP2 in CYH33-sensitive ESCC cells.