Figure 2. Effect of recombinant SFRP4 (rSFRP4) on SASP. (A) Comparison of the percentage of SA-β-gal-positive cells. rSFRP4 treatment increased SA-β-gal expression in proliferating cells. (B) RT-PCR analysis of the SASP gene expression. GAPDH was used as the housekeeping gene. (C) ELISA for protein expression of IL6 and IL8. (D) Western blot analysis of the effects of SFRP4 administration on confirmation and senescence. rSFRP4 treatment was observed to increase SASP at the mRNA and protein levels. rSFRP4; recombinant SFRP4. *; P < 0.05. Mann–Whitney U test was used to analyze differences between two groups. All experiments were performed in triplicate.