Bone marrow adipocytes are distinct from epididymal adipocytes. Bone marrow adipocytes and epididymal adipocytes were isolated from the same mice (age 6-month, 14-month and 18-month-old). Cells from several animals were pooled to yield sufficient sample to analyze three arrays for each age group and both adipocyte populations. A total of 18 arrays were included in the microarray analysis. A. Principal component analysis of array data before normalization showing clustering of bone marrow adipocytes as separate from epididymal adipocytes. B. Supervised hierarchical cluster analysis of 27 genes in adipocyte differentiation following normalization of all data sets.