Figure 4

Knockdown of Sp1 induces G1 phase arrest and up-regulates the expressions of p21 and p27. (A and B) Knockdown of Sp1 caused accumulation of G1 population. The representative images are shown in A and the percentage of cell distribution in G1/G0, S and G2/M is illustrated in B. CNE2, HNE1 and HK1 cells were plated in 6-well culture plates and transfected with siSp1-1#, siSp1-2# or siNC for 72 h. Cells were harvested, fixed, stained with propidium iodide and then analyzed for DNA content by flow cytometry. * P < 0.05, ** P < 0.01, *** P < 0.001. (C and D) Knockdown of Sp1 enhanced the expressions of p27 and p21. CNE2, HNE1 and HK1 cells transfected with siSp1-1#, siSp1-2# or siNC for 72 h were analyzed for the levels of cell cycle related genes by qRT-PCR (C) and Western blot (D). For (C), the mRNA level of the indicated gene was normalized to β-actin. * P < 0.05, ** P < 0.01, *** P < 0.001. For (D), α-tubulin served as an internal control.