Although influenza virus cannot block transcription initiation and still obtain 5′ capped mRNA, infection inhibits Pol II elongation on β-actin and DHFR genes early in infection (Chan et al., 2006) and induces cellular Pol II degradation later in infection (Rodriguez et al., 2007, Vreede and Fodor, 2010, Vreede et al., 2010). Here, DHFR is linked to infection.