The most essential genes, as indicated by a more negative efficacy score, included both well-established genes ubiquitous in MM biology, including NFKB1 and PRDM1, but also others such as IRS1. Genes with a high selectivity score included MEF2C, NFKB1, RELB and IRS1. MEF2C and NFKB1 were both essential for MM and had high selectivity scores (Supplementary Table 1b). Here, MEF2C is linked to Miyoshi myopathy.