Figure 5.

Insulin does not alter TGF-β1 mRNA stability. HK-2 cells were growth arrested before inhibition of transcription by the addition of actinomycin-D (500 ng/ml). Total cellular RNA was isolated throughout the following 12 hours either from untreated cells (constitutive TGF-β1 mRNA stability) or after addition of insulin (5 μg/ml) (A). Alteration in the stability of d-glucose-induced TGF-β1 mRNA was determined by RT-PCR (B). Scanning densitometry confirmed that there was no difference in the ratio of TGF-β1 mRNA to the housekeeping gene between the two experimental conditions (one representative experiment of four is shown).