However, in view of the staining of a small number of nuclei observed in treated hearts both by BrdU uptake (Figures 6B,C) and by staining for PCNA (Figures 7B,C), we cannot regard these observations as conclusive evidence that there is a complete absence of proliferating cells in post-MI hearts treated with α-gal nanoparticles. The gene discussed is PCNA; the disease is myocardial infarction.