Effects of ERG expression on B cells. (A-B) Colony-forming ability of control and ERG-transduced pro-B cells derived from BM. Number of colonies formed and rounds of plating (A), and photomicrographs of the colonies; original magnification ×40 (UPlan FLN 4×/0.13 PhP objective) (B). (C) Kaplan-Meier survival curve for mice that received a transplant with the indicated number of N-rasG12D- or ERG-expressing pro-B cells. (D) Equal numbers of GFP- and KO-, or ERG- and KO-expressing pro-B cells were transplanted into NOD-SCID mice, and BM and spleen cells were analyzed for expression of GFP and KO after the transplantation. FACS analyses for expression of GFP and KO in pro-B cells before transplantation (left) and in BM and spleen after transplantation (middle). A plot is presented showing the ratio of GFP to KO (right). (E-F) FACS analyses of GFP⁺ cells in BM and spleen of mice that received a transplant with pro-B cells infected with control or ERG virus (E) and of mice that received a transplant with BM cells infected with a lentivirus containing the CD19 promoter driving GFP-only control and ERG expression in the B-cell compartment (F).