Fig. 4.

ATRX is required for maintenance of HP1γ SAHF in senescent cells. a LS8817 cells were treated as described. b–d Cells were then fixed and the number of ATRX foci (b), the accumulation of SA-β-gal-positive cells (c), and the accumulation of four mRNAs of the SASP cytokine program (d) were measured. e Clonogenic growth was assessed after cells were replated at low density the absence of drug. Colony number is not quantified as individual colonies could not be discerned. f The accumulation of HP1γ-positive cells (SAHF) was determined. Representative images are shown (left) and the percentage of SAHF-positive cells was quantified (right). g HRAS mRNA levels were analyzed by qPCR. All data are represented as mean ± SEM from at least three independent experiments. Asterisk indicates p < 0.05 using a two-sided Students t-test. All images were taken at the same magnification. The scale bar is 20 microns