These fibroblasts in the tumor milieu are also called “CAFs.” Additionally, CAFs can transdifferentiate from other cells, such as pericytes, epithelial cells and ECs, via exposure to platelet-derived growth factor (PDGF), tumor-derived transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), MMPs and reactive oxygen species (ROS) (Cai et al., 2012; Yu Y. et al., 2014; Denton et al., 2018). This evidence concerns the gene FGF2 and neoplasm.