Similarly, our screen identified genes in each of these categories: 19 ribosomal genes including 14 RPL genes and 5 RPS genes; cell division and mitosis genes such as CDK1, INCENP, KMT5a, PLK1 and ZNF207; and proteasome/ubiquitin genes such as PSMD6, PSMD7, UBA52, UBB and UBC. Interestingly, the earlier screen on breast cancer cell lines [28] and our screen identified that knocking down the Notch inhibitory gene NUMB is cytotoxic. This evidence concerns the gene UBC and breast cancer.