HGF and cancer: In the tumor microenvironment, cancer-associated fibroblasts (CAFs) are the most abundant cells in the tumor matrix and promote tumor progression by secreting several growth factors, such as FGFs.189 Hepatocyte growth factor (HGF) secreted by CAFs specifically triggers PI3K/Akt signaling to affect cancer progression, and HGF has been detected in many types of human cancer, such as ovarian cancer.190 Furthermore, CCL5 derived from CAFs has been detected in ovarian cancer cells and shown to influence drug resistance by regulating PI3K/Akt signaling.191