For example, CCA cell lines harboring an IDH1 mutation are more sensitive to inhibition of Bromodomain and Extra-Terminal (BET), a family of epigenetic readers and transcriptional coactivators that combine acetylation of histone tails and recruitment of positive transcription elongation factor b (P-TEFb) (14, 15). The gene discussed is IDH1; the disease is cholangiocarcinoma.