Dual role of the adaptor protein SLP-65: organizer of signal transduction and tumor suppressor of pre-B cell leukemia.

B cell development is characterized by a coordinated progression through defined stages that are controlled at several checkpoints. Signals from the pre-B cell receptor (pre-BCR) are essential for regulated transition from the pre-B cell stage. The adaptor protein SLP-65 plays a key role in this signaling pathway. Recent findings indicate an additional function of SLP-65 as a tumor suppressor that regulates pre-B cell proliferation. We will discuss here the potential mechanisms by which SLP-65 controls the pre-B cell checkpoint.