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. Author manuscript; available in PMC: 2014 Mar 1.
Published in final edited form as: Cancer Discov. 2012 Nov 21;3(3):338–349. doi: 10.1158/2159-8290.CD-12-0313

Figure 7. NF1 critically regulate KRAS and HRAS in melanomas.

Figure 7

A) (left) In WM1976 melanoma cells that retain NF1 expression, RNAi mediated suppression of NF1 results in the activation of H- and KRAS, but not NRAS. (bottom right panels) NRAS-GTP assay confirming that NRAS is active in melanoma cells with an activating NRAS mutation (WM3629), but not in melanoma cells wild-type for NRAS (A375). B) Ectopic expression of the catalytically active NF1 fragment (GAP-related domain, GRD) suppresses H- and KRAS, but not NRAS activity in melanoma cells (MALME3M). RAS-GTP levels were assessed using a RAS pulldown assay. Immunoblots on total cell lysates are shown. C) shRNA mediated suppression of H- or KRAS, but not NRAS, suppresses the ability of A375 cells to proliferate and D) form colonies in soft agar. E) Confirmation of RAS isoform-specific knockdown by shRNAs in A375 cells. F) shRNA mediated suppression of H-, K- and NRAS suppresses the ability of WM3629 cells to proliferate and G) form colonies in soft agar. H) Confirmation of RAS isoform-specific knockdown by shRNAs in WM3629 cells. I) Suggested model for the distinct roles of NF1 in melanomagenesis.