The Hedgehog pathway regulates fibroblast activation. (A) Stimulation of human cultured fibroblasts with Shh induced stress fiber formation in resting fibroblasts to the levels that can also be achieved by TGF-β stimulation. Stress fibers were visualized with phalloidin and quantified with ImageJ Version 1.44p software. (B) Incubation of human dermal fibroblasts with Shh increased the mRNA levels of col 1a2 as well as the release of collagen protein (C) similar to that obtained on stimulation with TGF-β (n = 5 each).