IGF2 and neoplasm: Nevertheless, this hypothetical theorem for imprinted paternal expression of tumor suppressor genes towards growth may not be generally applicable to other tumor suppressor genes, given that Igf2r is a maternally expressed imprinted gene in mice and inhibits embryonic growth [45] and DIRAS3 is a paternally expressed imprinted gene in humans (and in pigs, submitted for publication by our group) and also hinders growth [46,47,48], and both counteract the effects of growth promoting Igf2 and RAS, respectively.