CBFβ-SMMHC inhibits p53 induction but induces p21WAF1/CIP1 in Ba/F3 cells exposed to IR or VP-16. (A) MTCB6 cells (vector-transfected) and MTINV-2 or MTINV-3 cells (expressing CBFβ-SMMHC from the MT promoter) were cultured ± 100 μmol/L zinc chloride for 18 hours. Half of the cells from each of these four cultures were then irradiated to 10 Gy. Cells exposed initially to zinc were continued in zinc after irradiation. Total cellular protein extracts were prepared 90 minutes later and electrophoresed on a 10% sodium dodecyl sulfate–polyacrylamide gel. The proteins were then transferred to a nitrocellulose filter, which was stained with Fast Green to control protein loaded (bottom panel) and subjected to Western blotting with antisera specific for murine p53, p21WAF1/CIP1, and CBFβ. The latter antisera detected CBFβ-SMMHC, which was induced by zinc in the MTINV-2 and MTINV-3 cells. (B) MTCB6 and MTINV-3 cells were cultured ± zinc for 18 hours. The cells were then exposed to 8 μg/mL VP-16 for 150 minutes in the presence or absence of IL-3. Total cellular extracts were then prepared and subjected to Western blotting for p53, p21, and CBFβ, with CBFβ levels serving as a control for protein loading.
