Given that PUMA is a key factor in TRP53-mediated apoptosis in haematopoietic cells [1, 12, 13, 15], it is perhaps not surprising that the majority of sick Puma−/−Zmat3−/− and Puma−/−p21−/−Zmat3−/− mice presented with lymphoma. Here, TP53 is linked to lymphoma.