RNase from frog R. pipiens has high anti-cancer activity, acts specifically on tumor cells, but does not affect normal healthy cells, and therefore it is called onconase. This RNase has a small size; its polypeptide chain is about ten amino acid residues shorter than that of RNase A due to mutations leading to the loss of amino acids which contact RI, so onconase does not interact with RI [27, 29, 45]. Here, RNASE1 is linked to cancer.