FIGURE 6.

Expression of tumor suppressor proteins in BALB/c 3T3 cells after arsenic exposure. A, arsenic treatment reduces expression of tumor suppressor proteins such as p16^INK4a or p19^ARF in BALB/c 3T3 cells. Lysate proteins were resolved by 10% SDS-PAGE and the protein bands were visualized by Western blotting with specific primary antibodies and an HRP-conjugated secondary antibody. Detection of total β-actin was used to verify equal protein loading. B, exposure of arsenic inhibited mRNA expression of p16^INK4a or p19^ARF in BALB/c 3T3 cells. RT-PCR analysis was performed to detect gene transcription using specific primers for p16^INK4a, p19^ARF, or β-actin (B, right panel). Total RNA was isolated from BALB/c 3T3 cells treated or not treated with arsenic as described under “Experimental Procedures.”