MMP2 and melanoma: It has been demonstrated that shikonin (a naphthoquinone pigment extracted from the dried root of Zicao (Lithospermum erythrorhizon, Onosma paniculata, or Arnebia euchroma, as a traditional Chinese herbal medicine) could block the phosphorylation of STAT3, decrease the levels of STAT3-targeted genes involved in melanoma survival and migration (Mcl-1, Bcl-2, MMP-2), and finally suppress melanoma growth [51, 52].