In 2008 Faca and colleagues took an innovative approach by using Pdx1-Cre Ink4a/Arflox/lox and KrasG12D Ink4a/Arflox/lox genetically engineered mice in order to sample blood from normal, early PanIN, advanced PanINs, locally advanced cancer, and metastatic cancer [30]. This evidence concerns the gene CDKN2A and metastatic malignant neoplasm.