Gene levels of cross-hybridization. Cross-hybridizing detected genes from the disjoint gene catalog using the microarray platform. (a) Percentage of human genes that are detected in each sample using the human microarray chip. (b) Percentage of mouse genes that are detected in each sample using the mouse microarray chip. (c) genes that cross-hybridize are identified by subtracting the genes detected in a homogeneous tissue sample (the “A” set) from the union of the mixed tissue samples (B,C, &D).