Comparison of BLIN-2 and normal pro-B cell growth on BM stromal cells. BLIN-2 and FACS-purified normal pro-B cells were plated at 2.5 to 5.0 × 10⁴/well on BM stromal cells and cultured in X-VIVO 10/0% FBS. The pro-B cells were supplemented with 10 ng/mL of IL-7. BLIN-2 and pro-B cell numbers were quantified on day 7 and replated onto fresh BM stromal cells (transfer 1) at the initial cell concentration of 2.5 to 5.0 × 10⁴/well. Quantitation of cell numbers and replating onto fresh BM stromal cells was repeated on day 14 (transfer 2) and day 21 (transfer 3).