UPK3A and infection: Although infection of COS-7 cells with recombinant adenoviruses encoding either UPIIIa alone did not result in detectable uroplakin expression, co-infection of COS-7 cells with UPIb and UPIIIa viruses resulted in a significant surface UPIIIa expression detectable using either AU1 or P3 antibodies (Figure 4B iv–viii) [19],[23].