DNASE1 and neoplasm: ExDNA was isolated from blood as described in the Materials and Methods section, and measurements of the concentration of exDNA in the pooled samples showed that in the blood of healthy animals, the exDNA level was low (77 ng/ml) and tumour development was characterized by a two-fold increase in the exDNA level (162 ng/ml), while DNase I treatment led to a decrease in the exDNA level (110 ng/ml), closer to healthy animals than to the control group (Table 1).