A, B, OTUB1 overexpression promotes serum-induced activation of endogenous wt RAS (A) or wt NRAS (B). GTP-bound RAS was pulled down from HEK293T cells expressing HA-tagged OTUB1 or empty vector (V) using recombinant RAF1 RBD conjugated to agarose beads. Input was controlled by immunoblotting using anti-panRAS or anti-Flag antibodies 