Ribonuclease K6 (RNASE6) is a secreted protein that belongs to the pancreatic ribonuclease family. Human RNASE6 is synthesized as a 150 amino acid precursor that contains a 23 amino acid signal sequence, and a 127 amino acid mature chain. RNASE6 is expressed in many tissues, with high expression levels in the lung, with lower expression levels in the heart, placenta, kidney, pancreas, liver, brain, and skeletal muscle. It is also detected in monocytes and neutrophils. RNASE6 may have a role in host defense.