RNPC3 and infection: To determine the role of the actin cytoskeleton in the nuclear export of influenza RNP complexes, we inhibited actin polymerization with the use of cytochalasin D. Treatment of MDCK cells with cytochalasin D 2 hours after infection with influenza delayed the nuclear translocation of RNP complexes (Fig. 8 D), indicating the importance of the actin cytoskeleton in this process.