In apoptosis assays, HE4 shRNA knockdown resulted in an increase in apoptotic cells at 5 days post-infection in PC-9, from 5.4% in the pLKO-treated cells to 17.5% in HE4 shRNA1 or 32.4% in HE4 shRNA2-treated cells (Fig. 2I and Suppl. This evidence concerns the gene WFDC2 and infection.