Ribonuclease 4  Ribonuclease 4 is an enzyme that in humans is encoded by the "RNASE4" gene. The protein encoded by this gene belongs to the pancreatic ribonuclease family. It plays an important role in mRNA cleavage and has marked specificity towards the 3' side of uridine nucleotides. Alternative splicing results in two transcript variants encoding the same protein. This gene and the gene that encodes angiogenin share promoters and 5' exons. Each gene splices to a unique downstream exon that contains its complete coding region.