POSTN and colonic neoplasm: Considering that CAFs are highly heterogeneous, despite the fact that several candidate markers such as α-smooth muscle actin (α-SAM), also known as actin alpha 2 (ACTA2), fibroblast activation protein (FAP), and periostin (POSTN) have been identified and commonly used in colon cancer, it is still challenging to precisely define CAFs populations [15].