Flow cytometric output for the EGFR and ErbB4 receptors expression after 24-hour EPR treatment in the H357 cell line. The outputs for the untreated control are represented by B and F. C and G, D and H, and E and I represent outputs for cells treated with 1 ηg/ml, 10 ηg/ml, and 20 ηg/ml of EPR respectively. The true percentage of cells and the density of expression of the EGFR or ErbB4 receptors were calculated by subtracting the autofluorescence of the unstained cells (not shown) from the fluorescence of the cells stained with the anti-EGFR-FITC or anti-ErbB4-PE antibodies (B–I) respectively. A The R1 polygonal box represents the gating of the cells based on the forward and side scatter profiles to exclude cellular debris and doublet cells. A total of 10, 000 gated events were acquired for analysis. B–E The green dots within the R2 boxes represent the fluorescence of cells after staining with anti-EGFR-FITC antibodies. F–I The pink dots within the R3 boxes represent the fluorescence of cells after staining with anti-ErbB4-PE antibodies.