The presence of cytokines and autologous stroma inhibits the outgrowth of cytokine-independent p210- and p230-expressing pre-B cells.

Two days after retroviral-mediated gene transfer, mouse bone marrow cells were expanded in the presence of autologous stroma and cytokines. After 12 days, nonadherent cells were replated in the absence of cytokines (indicated by the arrows). Cells were serially analyzed for the expression of B220 (A) and cKit (B).