TP53 and lymphoma: Interestingly, high levels of p19ARF which are indicative of loss of TRP53 pathway function, were apparent in 2 out of 4 wt, 2 out of 5 Zmat3−/−, 2 out of 3 p21−/− but none out of 8 p21−/−Zmat3−/− lymphomas tested by Western blotting (Fig. 3D).