IGF1 and cancer: A study discovered that insulin-like growth factor 2 (IGF2) and insulin-like growth factor 1 (IGF1) secreted by CAFs bind to IGF1-type receptors (IGF1R) on cancer cells, respectively, and activate the downstream Hippo-YAP1 and Akt/mTOR signaling pathways to promote the progression and metastasis of CRC (27, 28).