RNPC3 and infection: Therefore, to detect a possible interaction between E1B 55K and viral late mRNA in the context of infection, an RNA immunoprecipitation assay (RIP) was performed, in which total protein lysates of cells infected with the Ad5 WT or E1B− viruses or with the RNP mutants C288A, C288S, Δ284–289, and W289F were immunoprecipitated with the anti-E1B 55K MAb-2A6, and the pulled-down RNA were amplified by RT qPCR (Fig 1).