TGFB1 and neoplasm: To determine to what extent TGF-β protein levels correlate with mRNA levels, we compared TGF-β isoform mRNA levels determined using Affymetrix microarrays (4 tumors/model) with protein levels assessed by acid-ethanol extraction (5 independent tumors/model) for a total of 12 different mouse tumor models representing a range of TGF-β levels, and plotted the median values for each model and approach (Figure 1E).