Here, we show that cancer cells of human pancreatic ductal adenocarcinoma (PDA), colorectal cancer, and breast cancer are coated with transglutaminase-2 (TGM2)–dependent covalent CXCL12–keratin-19 (KRT19) heterodimers that are organized as filamentous networks. Here, KRT19 is linked to pancreatic ductal adenocarcinoma.