CAFs represent the most numerous populations in the tumor stroma, contributing to carcinogenesis by excreting diverse factors (α-smooth muscle actin (α-SMA), fibroblast activation protein α (FAPα), and fibroblast specific protein-1 (FSP-1)) that regulate intercellular signaling in tumor cells, and mechanically restore cancer tissue [96,97,98,99]. Here, FAP is linked to neoplasm.