Fig 4. Cell-free nucleic acids are only a few hundred base pairs long.

A) qRTPCR for human actin using increasingly larger amplicon size shows a loss in signal for the cell-free fraction (7,500 RPM supernatant) for amplicons > 180bp. ^# Undetectable. B) Comparison of Ct values between the 240bp and 60bp amplicon shows that there is a four-fold higher loss in signal for the cell-free (7,500 RPM supernatant) than cellular fraction (7,500 RPM pellet).