MAPK1p.D321N was a driver for HNSCC cell growth (22.3% growth increase vs. MAPK1-wild type (WT); P < 0.0001), while MAPK1p.R135K was unexpectedly a moderate suppressor for HNSCC cell growth (11.4% growth inhibition vs. MAPK1-WT, P < 0.0001; Fig. 1f). The gene discussed is MAPK1; the disease is head and neck squamous cell carcinoma.