Regarding iCCA, the determination of mRNA levels by RT-qPCR revealed that only MRP1 (gene symbol ABCC1) was a candidate prognostic biomarker; while the loss of breast cancer resistance protein (BCRP, gene symbol ABCG2) expression by immunohistochemistry, but not of MDR1 or MRP1, was associated with more aggressive tumor progression [33] (Figure 1). Here, ABCB1 is linked to neoplasm.