In silico gene rank–intensity plots from a first-generation platelet gene chip. Normalized data from individual microarray analyses obtained from 3 distinct leukocyte samples (A-C), 5 normal platelet samples (D-H), and 6 essential thrombocythemic platelet samples (I-N)⁹⁰  were analyzed by one-way ANOVA using parametric testing to identify a 432-member gene list. (top) Relative expression of the platelet-restricted genes (n = 389). (bottom) Expression intensity of the leukocyte-restricted genes (n = 43). Note the clear difference in the expression patterns between the 2 groups (leukocyte vs platelet).