To further assess whether MUC1 upregulation was mediated by soluble factors produced in the context of infection, we infected HAE with 5 × 104 PFU (approximate MOI of 1) of A/Udorn/307/72, transferred the virus-free basolateral medium collected at 48 hpi (46) to naive PMD macrophages, and then assayed MUC1 protein expression in macrophage culture lysates 24 and 48 h later (Fig. 5C). The gene discussed is MUC1; the disease is infection.