Fig. 4. Focal adhesion kinase (FAK) localisation in normal slow-twitch muscle. Immunocytochemical analysis of cross (A—D) and longitudinal (E,F) sections from slow-twitch normal soleus (N-SOL) muscle with the FAK N-terminal antiserum A-17 (A,E). Positive staining appears orange and nuclei appear blue. Control reactions of consecutive cryosections with normal rabbit serum are also shown (B,F). Arrows point to FAK-immunoreactivity at the sarcolemma. Consecutive sections were also stained for slow (C) or fast myosin (D) isoforms to determine the fibre types. All fibres, with the exception of two denoted type IIA, are of type I. Scale bars, 50 µm.