Hybridizations of arthroscopic samples (patients 8 to 13). (a) Barplot of the differentially expressed genes identified in the patient-by-patient comparisons between biopsies. In total, 1,536 unique genes were found to vary between the biopsies. (b) Hierarchical clustering (HCL) of the arthroscopic biopsies using all genes. Pt9_cc_2A, for example, refers to patient 9, distance to cartilage (ncc, not close to cartilage, cc, close to cartilage), biopsy 2, technical replicate A. Color codes: red, upregulated genes; green, downregulated genes; yellow, genes showing no change; white, missing values. (c) HCL analysis based on the subset of differentially expressed genes from (a) that was present in one or more comparison (421 genes).