CRK and melanoma: Using mouse melanoma tumors expressing wildtype Paxillin, which already exhibit low levels of Paxillin Y118 phosphorylation in vivo (Fig. 3, C and D), indeed we found that a significantly higher amount of CRKII and DOCK180/RacGEF interacted with wildtype Paxillin in cells in vivo versus cells in culture (Fig. 5, L–N).