PGP and breast cancer: In the next stage, five compounds with IC50 values on MV4-11 cells lower than 30 μg/mL were tested for their antiproliferative activity against MCF-7 (breast cancer), LoVo (colon cancer) human cell lines and also against Doxorubicin-resistant colon cancer LoVo/DX (P-gp-dependent, MRP-, LRP-dependent multidrug resistance).