PTK2 and melanoma: Interestingly, some melanoma cell lines with a more differentiated initial phenotype, such as UACC62 [15] and M229 [20], might tend to utilize RhoA signaling rather than Rac1 signaling as part of their adaptive response to BRAFi [42], and a recent study has implicated RhoA signaling in activating a FAK-driven drug resistance pathway in melanoma cells [34].