Rapamycin downregulates p70S6K (Thr 389) in GFb cells. Cells were treated with 10, 50 and 100 nM rapamycin for 3, 6, 12 and 24 h, and the expression of p70S6K, and p70S6K (Thr 389) were measured by Western blot. (A) Treatment with 10 nM. Phosphorylation of p70S6K (Thr 389) decreased after treatment for 12 h; (B) Treatment with 50 nM. Phosphorylation of p70S6K (Thr 389) was suppressed after 3 h; (C) Treatment with 100 nM. Phosphorylation of p70S6K (Thr 389) fell significantly after treatment for 3 h; (D) The resolved bands were quantified using Gel-Pro Analyzer 4.0 (Media Cybernetics, Inc., Rockville, MD, USA).