IL-15.E2A.mClover3 knock-in into IL-13 locus: (a) Transgene expression was evaluated by flow cytometry of GFP+ T cells 10 days post-electroporation; left panel, representative flow plots (samples electroporated without template DNA (-DNA) served as controls); right panel, summary graph of left panel (n = 8, two-tailed t-test; *** p = 0.0004). (b) Fold increase of knock-in efficiency without (-) or with (+) T-cell activation (n = 6, two-tailed t-test, *** p = 0.0005) (c) Knock-out of IL-13 was confirmed by IL-13 secretion; Ctrl, control knock-out; -DNA, knock-in without DNA template; +DNA, knock-in with DNA template (n = 3–11, one-way ANOVA, * p = 0.036 ** p = 0.007). (d) IL-15 expression from IL-13-edited (10 days post-electroporation) T cells 24 h post-T-cell activation (n = 4, two-tailed t-test, ** p = 0.005).