The majority of sick Puma−/−Zmat3−/− and Puma−/−p21−/−Zmat3−/− mice presented with lymphoma (Figs. 4B, S5, Table 1) as determined by histopathological analysis, while most sick Zmat3−/−p21−/− mice presented with solid tumours (Table 1). This evidence concerns the gene BBC3 and lymphoma.