Western blot analysis DBT cells in 6-well plates were infected with MHV-A59 and cytoplasmic extracts were prepared as described previously (Li et al., 1997) at various hnRNP A1 modulates cytoplasmic viral RNA synthesis time points p.i. The extracts were electrophoresed on a 12% polyacrylamide gel and transferred to a nitrocellulose membrane for western blotting.