When 2 × 106 of these cells were subcutaneously injected into both flanks of five female BALB/c nude mice, none of the mice injected with either of the two Irs4-knockdowns developed tumours, whereas we observed tumour growth in both flanks of all five mice injected with 2 × 106 GFP–shRNA control cells after 2 weeks (P=1.95 × 10−4, log-rank test) and in a subsequent experiment with 1 × 106 injected cells after three weeks (P=2.51 × 10−4, log-rank test; Fig. 2h). Here, IRS4 is linked to neoplasm.