HCK and arthritic joint disease: We and others have previously shown that myeloid Src-family kinases (Hck, Fgr and Lyn)32, Syk31, 37 and PLCγ2 (refs 29, 30) are required for immune complex-induced neutrophil functions and the K/B × N serum-transfer arthritis, supposedly by forming a receptor-proximal signalling cluster.