SPARC and melanoma: In addition, α6β1that was shown to promote the metastatic phenotype of melanoma cells [52, 53] is transcriptionally regulated by TGFβ that interacts with SPARC through reciprocal activation [2]; Thus, it is tempting to hypothesize that a link might exist between SPARC, B-Raf, α6 integrin and N-cadherin that inactivates Rac1.