Analysis of USF1 and USF2 bindings to the TME in rat megakaryocytes. ChIP assay was performed using purified rat megakaryocytes. Antibodies for USF1 and USF2 or isotype-matched controls were used. Precipitated DNA fragments and 10% of total DNA samples were amplified by PCR using primers specific for the rat PF4 promoter (–300 to –182), including the TME (–219 to –182), or primers for Hprt as a control. PCR products were separated on a 2% agarose gel and stained by ethidium bromide. (–) indicates no antibody.