However, UVA1 is unable to penetrate pigmented skin at an effective level to activate matrix metalloproteinases (MMPs). The investigators' preliminary data show that high dose UVB (160 mJ/cm2) will penetrate pigmented skin and activate the cellular pathways necessary to stimulate MMPs. They postulate, therefore, that in pigmented skin, higher than usual UVB doses can improve these fibrosing skin conditions safely through collagenase-mediated removal of excess dermal collagen via activation of MMP pathways.