Induction of cyclin A1 by PML-RARα expression.
(A) Immunoblot showing induction of PML-RARα by ZnSO4(0.1 mmol/L, 24 hours) in U937-PR9 cells that were stably transfected with PML-RARα under control of a Zn2+-inducible promoter. On each lane, 30 μg protein was loaded, and the blot was probed with an anti-RARα rabbit polyclonal antibody (Santa Cruz Biotechnology). Protein markers are shown in kilodaltons. (B) Northern blot showing elevation of cyclin A1 RNA (upper panel) but not cyclin A (middle panel) when PML-RARα was induced by ZnSO4. Equal loading was shown by staining for the 18-strand RNA (18s RNA). PR9 cells were induced to express PML-RARα for 24 hours, and total RNA was isolated. On each lane, 20 μg RNA was loaded. (C) Immunoblot showing that cyclin A1 protein levels also increased after induction of PML-RARα in U937-PR9 cells (24 hours, ZnSO4). On each lane, 30 μg protein was loaded. The lower panel shows a nonspecific band recognized by the anti–cyclin-A1 antibody that served as an internal control for loading of protein.
