(a) Real-time PCR analysis of c-Myc mRNA in naïve NK cells from MycOE (Mycfsf/+ Ncr1Cre+) and littermate control (Mycfsf/+Ncr1Cre-) mice. (b) NK cells as in a, representative flow cytometric plots of CTV dilution after ex vivo culture with IL-2 and IL-15 for 3 days, in the presence or absence of IRE1α inhibitor 4μ8C (5 μM). (c-e) WT (Mycfsf/+ IRE1f/f Ncr1Cre-), IRE1NK (Myc+/+ IRE1f/f Ncr1Cre+), MycOE (Mycfsf/+ IRE1+/+ Ncr1Cre+) and MycOE IRE1NK (Mycfsf/+ IRE1f/f Ncr1Cre+) NK cells were pre-labeled with CTV and cultured ex vivo with IL-2 and IL-15. (c) representative flow cytometric plots and quantification of CTV dilution at day 3, and (d) representative flow cytometric plots of Ki-67 levels and quantification of percentage of proliferating cells (defined as Ki-67+ CTVlo) at day 3. (e) Absolute numbers of NK cells at day 6. n=5 mice/group in a, n = 2 mice/group in b and n= 4 mice/group in c-e. Technical duplicates in culture per mouse in b-e. All error bars represent mean with s.e.m.. ***p<0.001, ****p<0.0001. Data were analyzed by two-tailed one sample t-test (a), or one-way analysis of variance (ANOVA) with the Tukey post-test performed (c-e). Data are representative of 3 (b-e) independent experiments or pooled from 2 experiments (a).