Fig. 2

Drug screening identifies RAF and ERK as the mediators of IFNγ-induced growth inhibition. (A) Workflow for the drug screen. The orange dots on the Z-score plot indicate expected hits that rescue IFNγ-mediated growth inhibition but do not affect cell growth in the absence of IFNγ. (B) Z-score plot showing the hits from the confirmatory screen. Compounds that fall in the box that denotes a Z-score cutoff of 1.8 do not affect growth inhibition. Hits and targets of interest are labeled in colored text. Three separate JAK inhibitors were among the hits, as shown in green. Hits targeting the MAPK pathway proteins RAF (SB-590885) and ERK (BVD-523, ulixertinib) are shown in orange. BRAF V600E inhibitor Vemurafenib, labeled in blue, did not affect IFNγ growth inhibition. (C) Data from the pilot screen showing that inhibitors of RAF (left) and ERK (right) rescue growth inhibition in a dose-dependent manner. At lower doses, around 50 nM, both compounds can block IFNγ-mediated growth inhibition (orange bars). However, at higher doses, both compounds cause cell death in the presence (orange bars) or absence of IFNγ (blue bars). (D) Schematic showing the MAPK signaling cascade with the targets of drug screen hits marked with asterisks. See also Fig. S3