a, Proliferation of bulk T cell populations either mock treated or edited at the CCR5 or UMPS loci and cultured without supplementation of UMP or uridine. Graphs show viable cell counts as measured by trypan blue exclusion. b, Proliferation of a bulk T cell population after electroporation of an RNP targeting UMPS cultured either with high concentrations of uridine or UMP, or without nutrient supplementation. Data points in a, b represent means of 3 biological replicates. Data is from the same experiment shown in Fig. 1f. For statistical analysis on day 5 see Fig. 1f. c, InDel spectrum on day 5 after electroporation of T cells with RNP targeting UMPS, for samples cultured either with or without nutrients as indicated.