EBNA2 alone is sufficient for suppression of AID expression. Quantitative RT-PCR of AID mRNA levels (A,D) and Ig μ heavy chain (B,E), each normalized to CD19 in BL41/K3 (A-B) and BJAB/K3 (D-E) cells, at the indicated time points after addition of estrogen. (C) Western blot analysis of AID protein expression in BL41/K3 cells with or without estrogen. (A-B, D-E) mRNA copy numbers were determined in duplicate; mean and variance of the 2 values are shown.