Of note, in our control P53/R26+/+ cohort (n=39), one mouse spontaneously developed a thymoma with immature T-ALL characteristics; with low tumour latency, increased cKit protein levels as well as high Lyl1, Hhex, Mef2c mRNA expression that all correlated with elevated endogenous Zeb2 levels (Supplementary Fig. 8). This evidence concerns the gene HHEX and thymoma.