There were no significant differences between Osx-Mdm2fl/+ (Mdm2 haploinsufficient MSCs) and Vav-Cre;Mdm2fl/+ (Mdm2 haploinsufficient hematopoietic stem cells) in response to IR, as both groups developed severe thrombocytopenia. This evidence concerns the gene SP7 and Thrombocytopenia.