Indeed, by comparing the percentages of near-tetraploid metaphases of the E1A/Ras Hipk2−/− MEFs before and after in vivo passage (compare results in Figures 2D and 3E), an increase of cells with altered karyotype is detectable upon in vivo tumor growth, indicating a pro-tumorigenic role for these alterations. This evidence concerns the gene HIPK2 and neoplasm.