Figure 2

Characterization of RNA. RNA was isolated from tissue cores and from histological sections and RNA concentration was measured spectrophotometrically (A). RNA yield was converted to correspond to 3 tissue cores with an average length of 3 mm or to 1 tissue section (10 μm thick), respectively. Mean recoveries and corresponding standard deviations are shown for 17 IDC, 9 DCIS and 12 normal tissue cores (N) and for 40 tissue sections (S). Five RNAs were excluded from subsequent experiments because RNA yield was less than 0.45 μg. The quality of each RNA sample was tested on a Bioanalyzer. A representative, gel-like picture for each histological type is shown (B). RNA quality was further assessed by QRT-PCR and mean Cts of 3 control genes (GUSB, RPLP0 and UBB) are shown (C). One RNA sample from DCIS and 2 RNA samples from normal tissue were excluded from subsequent expression measurement because mean Ct values of control genes were more than one standard deviation higher than the mean of all Cts (arrows).