FGF-2 and the active from of TGFβ in HCL BM and spleen. Paraffin-embedded sections of HCL BM (n = 5) and spleen (n = 3) were stained immunohistochemically for FGF-2 or TGFβ by a triple-layer technique using ExtrAvidin-alkaline phosphatase as the final layer. Original magnification, × 40.