Fig. 4. P311 is a retinoic-acid-responsive gene in lung fibroblasts. (A) Quantitative RT-PCR showing induction of P311 mRNA in lung fibroblasts isolated from early postnatal mice following treatment with retinoic acid (RA; 1 µM), but not with fatty acids (FA; 0.1 µM) for 1 week. Mean ± s.d. from triplicate samples are shown. Asterisks indicate statistically significant (P<0.01) pair wise comparisons between 1 µM RA-treated and untreated samples (^*) and between 1 µM RA+FA-treated and untreated samples (^**). (B) Quantitative RT-PCR showing that treatment with a higher concentration of FA (1 µM) for 48 hours did also not induce P311 mRNA in lung fibroblasts isolated from early postnatal mice, and that the induction of P311 mRNA by RA is dose-dependent. Note that treatment with 1 µM RA at 48 hours induced P311 mRNA to a similar extent as treatment for 1 week as shown in panel A. Mean ± s.d. from triplicate samples are shown. Asterisks indicate statistically significant (P<0.01) pair-wise comparisons between 200 nM RA+FA-treated and 12.5nM RA+FA-treated samples (^*) and between 1 µM RA+FA-treated and 12.5 nM RA+FA-treated samples (^**).