A, genomic PCR of control and Cre-transduced Abelson B-cells to detect the unrearranged (E2Aloxp) and deleted (ΔE2A) conditional E2A allele (17). B, RT-PCR analysis of total RNA from control Abelson pre-B-cells and three E2A−/− pre-B-cell lines. PCR for E2A (E47) and EF1α expression was performed on serial 3-fold dilutions of cDNA from each cell line. C, FACS analysis of E2A+/+ and E2A−/− pre-B-cell lines. Cells were analyzed for surface expression of the common pro-/pre-B-cell markers CD19 and CD43. D, expression of B-cell-specific genes in E2A−/− cell lines. Semiquantitative PCR was used to assess the relative expression levels of mb-1/Igα, B29/Igβ, EBF, and Pax-5/BSAP in control and E2A−/− cell lines. EF1α expression was used to verify equivalent sample loading.