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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Aging Cell. 2011 Oct 7;10(6):1038–1046. doi: 10.1111/j.1474-9726.2011.00746.x

Fig. 5.

Fig. 5

Smurf2 regulates the expression of p16. (A) Smurf2 (S), C716A (C) or C2 control was expressed in early passage human fibroblasts. Expression of p16 was analyzed in Western blot and quantitative RT-PCR. Relative transcript levels of p16 in cells expressing C2 were set to be 1 after normalization with β-actin. (B) The expression of Smurf2 was knockdown by shRNA in senescent human fibroblasts. Expression of p16 was analyzed in Western blot and quantitative RT-PCR. Relative transcript levels of p16 in cells expressing a non-silencing shRNA (NS shRNA) were set to be 1 after normalization with β-actin. Error bars were calculated from standard deviations of at least three independent experiments. Two-tailed and unpaired Student t–test was used in statistical analysis, and statistic significance is indicated as: * (P<0.05), ** (P<0.01), and *** (P<0.001). (C) The expression of Smurf2 was knocked down by stably expressed shRNA in mid-passage LF1 fibroblasts. The expression of Smurf2, p16, Id1 and Id3 was determined in Western blot, and replicative lifespan was determined by serial passage of cells expressing Smurf2 shRNA or non-silencing shRNA control.