IHC staining of murine bladder urothelium further demonstrated robust nuclear expression of both GATA4 and GATA6 in superficial umbrella cells which strongly co-expressed UPs as detected using a pan-uroplakin antibody (Figure 4C). These results demonstrate that both in vitro and in vivo expression of UP is associated with the presence of nuclear GATA4/6. The gene discussed is GATA6; the disease is undifferentiated pleomorphic sarcoma.