CDA and pancreatic ductal adenocarcinoma: Activated platelets in tumor cells release ADP in the extracellular compartment, and ADP-activated P2Y12 in pancreatic ductal adenocarcinoma (PDAC) increased expression of markers for gemcitabine resistance like human equilibrative nucleoside transporter 1 (hENT1) and cytidine deaminase (CDD) (350).