Staining on the tissue sections of injected xenografts of the p53 functional IGRG121 at day 5 of ONYX-015 108 PFU × 5 treatment revealed major preapoptotic and apoptotic changes in 3.1% of tumour cells, displaying compaction or segregation of the nuclear chromatin, or breaking up of the nucleus into discrete fragments (Figure 5R). This evidence concerns the gene TP53 and neoplasm.