PGP and adenocarcinoma: Eight selected compounds were then tested in doxorubicin-resistant human adenocarcinoma colon cells (HT29/DOX) and in doxorubicin-resistant non-small cell lung cancer cells (A549/DOX), that overexpress both P-gp and hCA XII [19], to verify the synergistic effect on the MDR reversal activity due to the dual P-gp/hCA XII inhibition.