Similar to the analysis performed with CCA tumors and normal healthy tissue, down-regulated signaling pathways in CCAs when compared to HCCs also included cholesterol metabolism, several cancer signaling cascades including chemical carcinogenesis, complement and coagulation cascades, PPAR pathway, bile secretion/synthesis, peroxisomes, and ABC transporters, as well as metabolic signaling pathways including fat digestion/absorption (Figure 2(E-2), right bottom panel and Supplementary Table S2C). The gene discussed is ABCG2; the disease is cancer.