TGFβ induces growth inhibition and senescence.

<p>A) The TGFβ data-set from GSE15871 was compared to probe-set changes between P3 and P5 wild type MEFs. Data was analyzed and is presented as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035460#pone-0035460-g005" target="_blank">Figures 5</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035460#pone-0035460-g007" target="_blank">7</a>. B) The culture conditions over passages 2 to 5 are shown schematically: Arrows below indicate times at which TGFβ (1 pM or 3 pM) was added for the 3T3 assay. The time of addition of TGFβ and EdU is shown above, and the time at which the SAβG assay was performed is shown below. Relative cell proliferation was measured at passage 3 and 5 in cells grown under standard conditions, followed by a single 24 hour treatment with TGFβ at the indicated concentration. The percentage of EdU positive cells is shown. C) Cell proliferation was determined in a 3T3 assay and is shown as cumulative increase in cell number. Cells were cultured under standard conditions or with the addition of 1 or 3 pM TGFβ at the times indicated in panel B. D) The percentage (average + s.d. of triplicate cultures) of wild type cells with positive SAβG staining is shown at passage 5, after continued treatment with 1 pM or 3 pM TGFβ, or under standard conditions. Significant differences between control and plus TGFβ are shown: * p<0.05, ** p<0.01, as determined by the Student's T test. E) A tentative model describing the involvement of Tgif1 and TGFβ in the pathways leading to cellular senescence.