Figure 2. MCM, Cdc45, and PCNA load in the final 4 hrs of G1 in Balb/MK cells.
(A) BrdU was pulsed into MK cells at the indicated times following release from quiescence to determine the kinetics of synchronization and entry into S-phase. (B) In parallel with the BrdU-pulsed samples in A, MK cells were collected at the indicated times and separated into total cell lysates (TCE), or fractionated into nucleosolic/cytosolic detergent-soluble extracts (S1) or chromatin-bound detergent-resistant extracts (P3). Immunoblotting with the indicated antibodies was performed on lysates from equal cell numbers loaded into each lane. The G1-S transition in MK cells (12 hrs after release) is overlayed in gray.