 We characterized the basis for the follicular lymphoproliferation in transgenic mice bearing a Bcl-2-immunoglobulin (Bcl-2-Ig) minigene representing the t(14;18) of human follicular lymphoma.     ///    Discriminatory S1 nuclease protection assays revealed that the Bcl-2-Ig transgene was overexpressed relative to endogenous mouse Bcl-2 in spleen and thymus. 