IDH1 and cancer: Since experimental screens are usually performed in cell lines, they can be negatively impacted by: (1) the limited representation of newly discovered mutations in existing cell lines: for example, the Cancer Cell Line Encyclopedia (CCLE) collection of 1,000 cell lines contains no acute myeloid leukaemia (AML) cell line with an oncogenic IDH1 mutation, even though the mutation is present in 10% of AML patients10, and (2) the artificiality of in vitro screening conditions11, 12, which cannot fully capture in vivo tumour evolution in the tumour microenvironment.