Effects of macrophage differentiation on mRNA distribution. Cytoskeleton-associated and cytosolic transcripts were isolated from HL-60 promyelocytic (precursor) cells and HL-60 differentiated to macrophage-like cells by phorbol ester induction. Microarray hybridization measured the relative amounts of 5184 mRNAs in the cytoskeleton and cytosolic populations of untreated or differentiated cells. Each of the 649 points represents the ratio of a specific transcript in the cytoskeleton-associated vs cytosolic fraction of the promyelocytic or differentiated cell type. Transcripts whose signal intensity was not above the background noise level were removed prior to analysis.