VEGFA and cancer: CAFs also promote cancer development by secreting growth-promoting factors such as TGF-β, stromal degrading enzymes and angiogenic factors such as MMP or VEGF, α smooth muscle actin (α-SMA) is a reliable biomarker for CAFs, and fibroblast activating protein α (FAP-α, seprase) is a surface glycoprotein that is selectively expressed on solid tumor fibroblasts.