Expression pattern of adaptor protein PAG: correlation between secondary lymphatic follicle and histogenetically related malignant lymphomas.

Transmembrane adaptor protein PAG, also known as Csk-binding protein (Cbp), which binds and activates the cytoplasmic tyrosine kinase Csk, the major negative regulator of Src-family kinases, was found to be expressed in germinal centers of lymphoid follicles as well as in follicular, but not mantle cell lymphomas. Expression of PAG may reflect its role in regulation of proliferation and differentiation of germinal center B-cells. From the routine histopathology point of view, PAG might be a new positive marker of follicular lymphoma and a negative marker of mantle cell lymphoma.