At this point, despite comparable initial levels of ICN expression (Fig. S5C, D) and low percentages of ICN-GFP+ in the PB (average 0.3% vs. 0.2%), Skp2−/− ICNns recipients exhibited increasing levels of WBCs and of T-cell leukemia blasts, whereas Skp2−/− ICNs recipients showed WBC counts and T-cell percentages comparable with the control group (Fig. 4e). Here, SKP2 is linked to T-cell leukemia.