Inhibition of pre-BCR relocalization impairs pre-BII-cell proliferation. (A) After BrdU incorporation, pro-B/pre-BI cells (B220⁺CD117⁺Igκ/λ⁻) were allowed to differentiate for 2 days in the absence of IL7 by coculture with stromal cells. Control experiments were performed using OP9-pSR cells in the presence of mSLCΔΔ. Pre-BCR relocalization was inhibited by adding mSLC in the medium, by performing cocultures with OP9-shG1 cells in the presence of mSLCΔΔ, or by adding mSLC and using OP9-shG1 cells. Data are representative of at least 4 independent experiments. The progressive loss of BrdU expression is representative of the proliferative activity of the cells. The mean fluorescence intensity (MFI) is indicated in each histogram. (B) Representation of BrdU expression (normalized MFI) for each condition described in panel A. Each point represents an individual experiment and bars represent the average values. P values were determined using the Mann-Whitney unpaired test with a risk of 5% (*P = .013, **P = .005).