However, CCA acquires resistance to gemcitabine through undergoing downregulation of equilibrative nucleoside transporters (ENTs) which is associated with gemcitabine uptake (101), and low expression of ENT1 is a biomarker for chemoresistance to gemcitabine in CCA patients (102, 103). The gene discussed is SLC29A1; the disease is cholangiocarcinoma.