KIT and thymoma: 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).