The expression of selected ABC transporters was analyzed using qRT-PCR upon siRNA/shRNA-mediated knockdown or exogenous overexpression of ΔNp73 in the breast cancer-derived cell lines MCF7 and MDA-MB-231, as well as in primary melanoma samples and in the melanoma-derived cell line SK-MEL-28. The gene discussed is ABCG2; the disease is breast carcinoma.