The discovery of extracellular circulating RNAs and the elucidation of their role in tumor progression and metastases spreading [21,22] suggested that these RNAs together with intracellular RNAs could be the molecular targets for RNase A. There have been attempts to identify molecular targets of RNase A in the tumor tissue and blood of tumor-bearing mice (with the example of Lewis lung carcinoma) [23]. The gene discussed is RNASE1; the disease is neoplasm.