In cancers with mTOR gain-of-function mutations, such as glioblastoma or renal cell carcinoma [103], CRISPR-Cas9 can be used to selectively knock out the mutated allele, thereby reducing excessive mTOR signaling, which could help control tumor growth driven by mTOR overactivation. The gene discussed is MTOR; the disease is hereditary clear cell renal cell carcinoma.