Because MMP3 activates the collagenases MMP1, MMP8 and MMP13 [30] that are capable of degrading collagen types I, II, III, V and IX as well as native fibrillary collagen [31] which is crucial for melanoma metastasis, we tested for MMP3 secretion by performing western blot analyses (Fig. 9b). Here, MMP1 is linked to melanoma.