(A) Nuclear extracts from clonal cell lines control Clone 1 (empty vector control), Clone 5 (cell line stably expressing FLAG-tagged ZFP809(1-353) or Clone 9 (cell line generated with same construct as Clone 5 but which does not express ZFP809) probed by western blot with antisera for FLAG (upper panel), TRIM28 (middle panel), or beta-actin (lower panel). (B) Nuclear extracts prepared either from PCC4 EC cells or cell lines control Clone 1, Clone 9, or Clone 5 used in EMSA reactions with radiolabeled probes corresponding to PBSPro (PRO) or PBSB2 (B2). In final three lanes the PBS silencing complex is supershifted by the addition of 2 µg of either anti-TRIM288, anti-FLAG, or a control anti-HA antibody. (C) ZFP809(1-353) and TRIM28 co-immunoprecipitate in DNase treated Clone 5 whole cell extracts in the presence of ethidium bromide. Control immunoprecipitations were performed with of HA antisera. Immunoprecipitated ZFP809(1-353) and Co-immunoprecipitated TRIM28 was detected by western blot.