Rituximab does not activate B cells.

Resting tonsillar B cells were stimulated with 2 μg/mL rituximab or 1F5 anti-CD20 antibodies. Total RNA was extracted at 3 hours (c-myc, lanes 1-3) or 48 hours (B-myb, lanes 4-6) and analyzed for expression of the indicated mRNA by Northern blot. The photograph of the ethidium bromide stained blots is shown below to demonstrate that all lanes contained equivalent quantities of RNA.