IGF1 and cancer: Paracrine IGF1/IGF1R signaling initiated by radiotherapy-activated cancer-associated fibroblasts promotes colorectal cancer progression (Tommelein et al., 2018), and the radiation-induced secretion of IGF1 in human fibroblasts up-regulated IGF1R/Akt signaling in bystander cells (Ivanov et al., 2010).