Comparison of infection of DOX− MUC1 cells with the MUC1-positive subset of cells in the DOX+ MUC1 cell population yielded 40% infected cells for the MUC1-negative cells (Q3/Q3+Q4) and 50% infected cells for the MUC1-expressing cells (Q2/Q1+Q2) (Fig. 1E). Here, MUC1 is linked to infection.