In a number of studies, an increase in the cytotoxicity of RNase A and RNase 1 was achieved by conjugating these RNases with peptides, proteins and antibodies, which increased the efficiency of their capture by tumour cells (Rybak et al., 1991; Newton et al., 1992; Psarras et al., 1998; Futami et al., 1999). Here, RNASE1 is linked to neoplasm.