Indeed, the ATRA IC50s were almost perfectly correlated with SMAD9 expression levels in both the GDSC (R = −0.92, P = 4.2 × 10−6; Fig. 2B) and DepMap (R = −0.81, P = 4.8 × 10−4; Fig. 2A, B), with SMAD9 expression also prognostic in neuroblastoma patients (Fig. S2B, C). Here, SMAD9 is linked to neuroblastoma.