Circulating DNA and oncoproteins can be extracted fi om serum or plasma of
cancer patients. In this study, using gel retardation analysis we observed
circulating DNA obtained from plasma of a lung cancer patient complexed wit
h serum proteins. p53 was identified by immunoblotting as one of the protei
ns present in the complex. Our finding suggests that the same interaction o
bserved between p53 and DNA in intact cells occurs in serum of lung cancer
patient. As far as we know this is the first evidence for such finding.