POSTN and malignant colon neoplasm: Research has shown that dipeptidyl peptidase IV (DPP4)-enriched exosomes, which are secreted by 5-fluorouracil-resistant colon cancer cells, mediate angiogenesis by increasing the expression and secretion of periostin (POSTN) (a proangiogenic extracellular matrix protein) via Twist1 nuclear translocation or activating the Smad signalling pathway [115].