RT-PCR tests of expression patterns of selected genes chosen by digital subtraction. RT- control reactions prepared from the same RNA were run for six of the PCRs shown here and no contaminating genomic DNA (gDNA) was ever found. For clarity, RT- control reactions run simultaneously have been cut out here. Positions of molecular weight markers on each side of the gel are shown. The sample identifiers are listed for each lane at the top of the gel (as for Figure 7).