FIG. 4.
JunB expression in B9SQ and A5SP cells. (A) Northern blot of 10 μg of two separate RNA preparations from B9SQ and A5SP cells. Probes are indicated to the right. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) served as a loading control. Probes had approximately the same specific activities. c-Jun exposure time was 96 h. JunB and JunD exposure times were approximately 12 h. Numbers beneath panels show the relative quantity of the transcript after normalization to the GAPDH loading control. (B) Immunoblot for the Jun family using 5 μg of nuclear extracts from B9SQ and A5SP cells. Jun antibodies are indicated to the right. (C) Overexpression of JunB in A5SP cells. (Top panel) Str-1 Northern blot of 10 μg of total RNA from A5SP populations stably transfected with empty vector or JunB expression vector. (Middle panel) JunB immunoblot of 5 μg of nuclear extracts prepared from A5SP JunB stable clones demonstrating various levels of JunB expression. (Bottom panel) Str-1 Northern blot of 10 μg of total RNA from the same clones as those shown in the middle panel.