KRAS and pancreatic ductal adenocarcinoma: Our previous results indicate that microRNAs could trigger key driver genes’ dysregulation such as K-ras in pancreatic ductal adenocarcinoma (PDAC), thus contributing to pancreatic cancer suppression [15–17]; microRNAs were also reported to be regulated by transcription factor (TF) because these microRNAs have binding sites on their promotor [18].