FIG. 3.

Reduced expression of wild-type Siah-1 protein and certain mutants is not due to reduced gene expression. (A) Northern blot analysis of the expression of SIAH1 transcripts following transfection of the SIAH1 cDNA constructs into COS-1 cells. The indicated SIAH1 expression constructs (lanes 1 to 5) or the empty vector control (lane 6) were transfected into COS-1 cells. Forth-eight hours after transfection, total RNA was extracted with Trizol reagent and Northern blotting was carried out. The blot was probed with a ³²P-labeled SIAH1 cDNA fragment. Similar levels of wild-type and mutated SIAH1 transcripts were observed, in all lanes except the negative control (lane 6). (B) Ethidium bromide staining of the RNAs verifies equivalent loading. The 28S and 18S ribosomal bands are indicated.