Analysis of the expression of a putative let-7a mRNA target, KRAS revealed significantly increased expression of KRAS (by 1.5 fold, P < 0.005, Supplementary Fig. 3A), in the pituitary tumours of Men1+/− mice, when compared to normal pituitaries of Men1+/+ mice, although a significant inverse correlation was not observed between the expression of KRAS and let-7a (Supplementary Fig. 3B). Here, MEN1 is linked to pituitary tumor.