HIF1A and neoplasm: Furthermore, transfection of reovirus genome into human tumor cell lines also downregulated HIF-1α protein levels, even in the presence of polyinosinic-polycytidylic acid (polyI:C), which is a synthetic double-stranded RNA analogue that acts as a pathogen-associated molecular pattern (PAMP), indicating that reovirus RNA plays an important role in this reduction [115].