Figure 5.

A model for transcriptional control of the pre-B-to-B transition. IRF-4,8 are depicted as components of a genetic switch whose function is to down-regulate expression of the surrogate light-chain genes, thereby inhibiting pre-BCR-dependent proliferation of pre-B cells. Concomitantly, IRF-4,8 promote pre-B-cell differentiation by inducing conventional light-chain gene transcription and rearrangement. These latter processes are proposed to depend on binding of IRF-4/8 to κ and λ enhancers with the transcription factors PU.1/Spi-B.