PDX1 and neoplasm: Based on RNA sequencing and tumor DNA methylation profiling, PanNETs have recently been classified into (1) tumors with an α-cell signature (carrying ATRX, DAXX, and MEN1 mutations with a high ARX and low PDX1 gene expression due to PDX1 promoter hyper-methylation) and (2) tumors with no ATRX, DAXX, and MEN1 mutations [43].