CXCL12 and neoplasm: In addition, suppressed expression of human equilibrative nucleoside transporter 1 (hENT1), specific pyrimidines such as deoxycytidine, released by tumour-associated macrophages (TAMs), epithelial-mesenchymal transition phenotype, miRNA, and pancreatic stellate cells (PSCs) in the tumour stroma, through SDF-1α/CXCR4 signalling, spur multi-level chemoresistance to gemcitabine, which is widely prescribed as a first-line drug [7,8].