Cancer-associated fibroblasts, key drivers of tumorigenesis

 To describe cancer-associated fibroblasts (CAFs) in the context of the tumor microenvironment.  To state the essential role of CAFs on tumor progression, invasion and metastasis by acting as key suppliers of tumorigenic molecules, signaling cancer cells in a paracrine fashion.  To review current preclinical and clinical trials on anti-cancer immunotherapy targeting CAFs or their crosstalk with cancer cells. 2. The tumor microenvironment