total RNA was extracted from individual rat mammary glands; 5 mu g of each RNA sample was reverse transcribed, synthesized to double-stranded cDNA, and then transcribed to biotin-labeled cRNA targets which were then fragmented. Equal amounts of fragmented targets were combined from the 12 individual rats in group b to give a total of 10 mu g of the fragmented cRNA targets. a is RXR treatment, b is control
