Effect of SM on BHRF1 expression. (A) BHRF1 mRNA expression in 293 BMLF1-KO cells. 293 BMLF1-KO cells were transfected with either empty vector plasmid (C), Z expression plasmid (Z), or Z and SM expression plasmid DNA (Z+SM). RNA was isolated, and Northern blotting was performed with a BHRF1-specific probe. (B) The blot in panel A was probed with a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) probe as a loading control. (C) BHRF1 protein expression in BMLF1-KO cells. BMLF1-KO cells were transfected as for panel A, and protein lysates were analyzed by immunoblotting with anti-BHRF1 antibody. Lane 1, BMLF1KO cells transfected with vector plasmid DNA (C); lane 2, BMLF1KO cells transfected with Z expression plasmid DNA (Z); lane 3, BMLF1KO cells transfected with Z and SM expression plasmid DNA (Z+SM). (D) The blot in panel C was stripped and reprobed with actin antibody.