Serum starvation induced cell cycle synchronization.

(A) and (B): Representative FACS data showed cell cycle arrested at G0/G1 phase (0 h) after serum starvation for 18 h. Re-feeding with FBS resulted in a clear accumulation of S and G2/M phase at the indicated time. (C): Modfit LT analysis revealed a time dependant increase in G0/G1 fraction upon serum deprivation. *P<0.01 vs control (n = 3). (D) and (E): A summary of cell cycle distribution after release from starvation. (F): Immunofluorescence revealed HDF and ASC increased BrdU incorporation after synchronization. Green fluorescence represents BrdU; the nuclei were labeled with DAPI (blue). Scale Bars = 20 µm. (G): Quantitative analysis indicated starvation and re-feed procedure increased BrdU positive cells in HDF. Counting was based on Brdu and DAPI staining. Positive cells were counted from a total number of at least 300 cells per well (n = 3) in randomly selected field. *P<0.01 vs unsynchronized control (n = 3). (H): Apoptosis assay of HDF after serum deprivation by Hoechst 33258 staining. *P<0.05 vs control (n = 3).