PGP and breast cancer: Screening of the antiproliferative properties of the synthesized 2-oxo-2-phenylethane sulfonamide 11 and chalconesulfonamides 7a–l was performed with an MTT test on breast cancer cells MCF7, hormone-resistant MCF7/HT2 subline [34], leukemia cell line K-562, resistant subline K-562/4 with Pgp [35,36], and colon cancer cells HCT-116.