Figure 9.
Activation of Src by MC1R signaling and possible role in downstream activation of the ERK pathway. A, Kinetics of Src activation in HBL cells (left panel) or HEK293 cells transfected with MC1R and cKIT (right panel) after stimulation with 10−7 m NDP-MSH (left panel). Src activation was assessed by decreased inhibitory Tyr530 phosphorylation. B, Lack of Src activation by FSK. HBL cells were treated with 10−5 m FSK for the times shown and tested for Src activation as in A. C, Effect of the Src inhibitors Na-PP1 (upper panel), PP-2 (middle panel), and Dasatinib (lower panel) on ERK activation mediated by NDP-MSH or by the constitutively active Q61R mutant of NRAS. HBL cells transfected with empty pcDNA3 or a construct corresponding to the Q61R NRAS mutant were preincubated with the Src inhibitors at the concentrations shown and then challenged with NDP-MSH (10−7 m, 5 min). ERK activation was estimated by Western blot.