Fig 1.

Ligand activation of PPARβ/δ attenuates cell proliferation by inducing G₂/M arrest, causing selection against cells expressing HRAS at high levels. (A and B) HRAS-expressing wild-type and Pparβ/δ-null keratinocytes were treated with or without 1 μM GW0742 for 4 days. Cell numbers were quantified daily. Cell cycle analysis was performed after 3 days of treatment. (C) Western blot analysis of HRAS-expressing keratinocytes 5 days or 11 days postinfection. Expression levels were normalized to β-actin and are presented as fold change relative to control DMSO results. (D) Flow cytometric analysis using anti-HRAS antibody was performed, and Pearson's second skewness coefficient was calculated for HRAS intensity. (E) Cells were infected with an Hras retrovirus at increasing MOI, and after 3 days of culture with or without 1 μM GW0742, an MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] assay was performed. (F) Flow cytometric analysis of HRAS intensity in HRAS-expressing keratinocytes performed as described above for panel D. For all data sets, n = 3 or 4 independent samples per treatment group. Values represent means ± standard errors of the means (SEM). *, significantly different from wild-type vehicle control (DMSO) result, P ≤ 0.05. #, significantly less than GW0742-treated wild-type result, P ≤ 0.05. Values with different superscripts are significantly different, P ≤ 0.05.