Suppression of endogenous LMP1 and LMP2A by siRNA results in apoptosis of EBV⁺ cells. (A) The cell lines indicated were transfected with a LMP1 siRNA (L1) or scrambled siRNA (s), or mock transfected (−), at days 0, 2, and 4, and assessment of apoptosis was performed by annexin V staining at day 6. Bars represent the average number of annexin V–positive cells (+ sem) of a representative experiment of 2 independent experiments for each cell line shown, where each transfection and analysis was performed in triplicate. (B) The indicated cell lines were transfected as in panel A, but in addition they were transfected with siRNA to LMP2A (L2) alone or in combination with siRNA to LMP1 (L1 + 2A) as indicated. Suppression of LMP2A was effective on its own in inducing apoptosis of the EBV⁺/type II/III cell lines tested, but did not enhance the effect seen with LMP1 suppression.