ABCC4 and neoplasm: Together with the knowledge that CTC cells from PDAC patients express higher levels of MRP4 compared to primary tumor cells, and that silencing MRP4 alters the expression of several CTC biomarkers, such as IL11, EBI3, VEGFA, and ADGRG136, our findings suggest that an upregulation of the transporter could confer an adaptive advantage associated with disease progression in PDAC patients.