FIG. 1.

Effect of dexamethasone on RET expression. (A) Assessing RNA expression using the TT cell line. Flasks were treated in triplicate with 10⁻⁶ M dexamethasone (Dex) or an equivalent volume of ethanol (EtOH) for 24 h. Total RNA (5 μg) was subjected to electrophoresis and Northern blotting. The resulting filter was hybridized to RET and 36B4 riboprobes concurrently. (B) Assessing protein expression using the TT cell line. Cells were treated in triplicate with 10⁻⁶ M dexamethasone or ethanol for 24 h as in (A) and 50 μg protein used for SDS-PAGE and Western blotting. Membranes were hybridized to RET and α-tubulin antibodies sequentially. (C) Assessing RNA expression using primary medullary carcinoma cells. Explant cultures from a 27-year-old woman with metastatic MTC were treated 1 day after establishment with vehicle (EtOH) or 10⁻⁶ M dexamethasone (Dex) for 24 h. The duplicate lanes shown after Northern blotting and hybridization were derived from single treatment samples; less was loaded in dexamethasone-treated lanes. A single lane of TT RNA was included for comparison with (A).