CR2 and Splenomegaly: The tumorigenic pre-B cell population was phenotypically similar to splenocytes from HIV Tg mice with splenomegaly and consisted of B220+/−CD19+CD43+CD93+pre-BCR+CD127+CD138+IgM+CD21+/−CD5+/−Sca1+ and CD34+/−, with B cell markers B220, CD21, CD5, CD138 and CD34 variably expressed and probably linked to the activation stage of the cells (Figure 5A and Additional file 1: Figure S7).