Figure 1

CDK1-catalyzed phosphorylation of interphase lamins A and C enhances their P-STM immunoreactivity. Total extracts (TE; 60 μg) from HeLa S3 cells treated for 14 h with DMSO (lane 1) or Noc (1 μg/mL; lane 2) were resolved by SDS-PAGE on 10% gels and immunoblotted (IB) with P-STM antibody or anti-lamin A/C antibody. Lamins A and C were immunoprecipitated (IP) from total extracts of unsynchronized cells (2 mg) and then in vitro-phosphorylated by incubating with CDK1 (lane 4) for 30 min; immunoprecipitates incubated without CDK1 (lane 3) served as controls. IP products were resolved by SDS-PAGE on 10% gels and analyzed by immunoblotting as described.