MMP1 and keloid: M. Fujiwara et al. investigated the MMPs in keloids and found that the levels of MMP-1 and MMP-2 are 6-fold and 2.4-fold greater than those fibroblasts in normal skin tissue, respectively, and the upregulation of MMP2 is associated with the signalling of TGF-β [34], a classical pathway in pathogenesis in keloids.