Indeed, our previous studies showed that tumour cells from Tsc1iΔEC mice, but not Tsc1-null ECs of non-tumour tissue (i.e. lung) of the same mice, readily form tumours when transplanted in nude mice.5 These results suggest that, while it is required, Tsc1 deletion and consequent mTORC1 hyper-activation alone may not be sufficient to induce and maintain LAS. This evidence concerns the gene TSC1 and neoplasm.