Beyond the MAPK/ERK pathway, the strongest markers of resistance to BKM-120 were AKT and p-BAD (p<0.001) Interestingly, BKM-120 IC50 values did not show a strong correlation with our previously published PI3K score [5] (Rho = 0.101, p = 0.51), which is consistent with published observations that sensitivity to pictilisib (GDC0941, a PI3Kα/δ inhibitor) showed no correlation with the PI3K score in a panel of 60 head and neck squamous cell carcinoma cell lines [36]. Here, PIK3CA is linked to head and neck squamous cell carcinoma.