IDH1 and neoplasm: The RB1 gene was the first tumor-suppressor gene to be molecularly defined.27 Dysregulations of the RB pathway signaling are a critical event in gliomagenesis.28 In our study, we identified that RB1 loss-of-function mutations are present in 10% of our institutional cohort and 14.6% of MSK-IMPACT GBM IDH-WT.