Immunohistochemistry scores of P-gp, Mrp1, and Bcrp1 in tumor tissue sections.

Protein expression was scored for quantity (percentage of cells, ranging from 0 = 0, 1 = <20%, 2 = 20–40%, 3 = 40–60%, 4 = 60–80%, to 5 = 80–100%), and intensity (0 = absent, 1 = low, 2 = moderate, 3 = high). Using these data, an immunohistochemistry score (IHS) was calculated by multiplying the quantity and staining intensity scores. IHS: 0 = negative, 1–3 = weak, 4–9 = moderate, 10–15 = strong.