To validate the RAC1 effector p110β as a potential combination strategy for BRAF-mutant melanoma, we compared the in vitro growth kinetics of a BRAF-mutant, PTEN-deficient melanoma cell line (WM266.4) and a BRAF-mutant, TP53-deficient but PTEN-proficient line (A375) following treatment with AZD8186, a clinically relevant, p110β/δ inhibitor (33). Here, TP53 is linked to melanoma.