Representative immunohistochemical images showing expression of the α1 integrin subunit in CRC (B, D, F, H, L) and corresponding matched resection margins (A, C, E, G, K). The α1 subunit was found to be expressed at higher levels in a significant number of CRC tumours (D, F, H) compared to their corresponding matched normal tissues (C, E, G) where it was found to be predominantly expressed in the proliferative cells of the crypt and below detection levels in normal surface epithelial cells (C, G). Note that the subepithelial myofibroblasts were also stained for α1 in both normal tissues (A, E, G) and tumours (B, D, F, H). Scores: The margin in A and the tumour in B were both scored 0 (negative) whereas the tumour in D was scored 2 (strong) compared to score 0 (weak) for the matched margin C. The tumour in F was scored 1 (moderate) as was its corresponding margin in E (moderate). The margin in G was scored 0 and the matched tumour in H was scored 2. To validate the specificity of the primary goat anti-α1 antibody, adjacent sections of the same normal (I, K) and cancer (J, L) specimens were stained using 5 μg/ml of non-immune IgG (I, J) or anti-α1 IgG (K, L) as primary antibody. Scale bars = 50 μm.