TGFB1 and cancer: CAFs promote cancer cell growth and metastasis by secreting various growth factors and cytokines, including TGFβ [11], stromal cell-derived factor-1 (SDF-1) [12], CXCL1 [13], tumor necrosis factor-α (TNFα) [14], as well as microRNAs [15, 16] and exosome [17, 18].