IRS4 and neoplasm: On subcutaneous injection in both flanks of five female BALB/c nude mice, tumour growth was observed in all flanks injected with NMuMG-Irs4 about five weeks post-injection, whereas the mice injected with vector control cells remained tumour-free for more than 10 weeks (P=3.13 × 10−3, log-rank test), after which tumour growth was sporadically observed in a single flank (Fig. 2i; Supplementary Fig. 2d).