Analyses revealed significant depletion of pre-crRNAs targeting murine homologues of known essential human genes over time (Figs. 2D, Supplementary Fig. S7A, B), such as Eef2 (as we saw in the lymphoma screens), as well as Psmb2 (β4) and Psma3 (α7), members of the 20S proteasome complex27. This evidence concerns the gene PSMB2 and lymphoma.