GCS-100 modulates cell-cycle regulatory proteins. (A-B) Western blot analysis of RPMI 8226 cells cultured with 500 μg of GCS-100 for up to 48 hours. Whole-cell lysates were prepared, 25 μg of protein was separated using 12% or 15% SDS-PAGE and after transfer to PVDF membrane was probed with the indicated antibody. β-Actin was used to ensure equal protein loading.