PGP and neoplasm: Consistent with the obtained data, DOXO treatment inhibited the cell proliferation at 48 h in two CMT cell lines: one from a primary tumor and one from a lymph node metastasis; furthermore, a substantial effect on the cell cycle was observed, as well as an increase in the gene expression of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP) compared to the controls [18].