Figure 5.

STRAP mediates Sp1 stability during cell cycle progression. (A) STRAP knock-down stable clones from HeLa cells with control cells were synchronized by serum-starvation for 72h and released by adding 10% FBS for the indicated time-points. Total cell lystes were analysed for Sp1, STRAP and β-actin expression by immunoblotting using respective antibody (upper panel). Cell cycle phase were monitored by flow cytometry (bottom panel). (B) HeLa cells were synchronized by serum-starvation for 24h and then co-transfected with HA-ubiquitin and Sp1-Flag or STRAP-Myc expression plasmids as indicated. After total 72 hours cells were released into fresh media, cell lysates were collected at different time-points, subjected to anti-Flag immunoprecipitation and then analyzed by immunoblotting with anti-Ubiquitin antibody. Blots are representative of three independent experiments.