CcpA expression levels in B. subtilis cultures used for DNA microarray experiments. (A) upper panel, CcpA detection using anti-CcpA antibody; lower panel, signal quantification with ImageJ. Four CcpA expression levels were achieved by growing B. subtilis strain MP902 (Ptet-ccpA, Pxyl-tetR) in absence (lanes 1, 3 and 5) and in presence of 0.1, 2 and 20 nM ATc (lanes 2, 4 and 6), respectively. All cultures were grown in presence of 0.2 % xylose and 1 % glucose. Shadows in the background of the picture indicate culture pairs used in microarray experiments (B) Ponceau S control membrane staining for protein load verification. Lane numbers correspond to lane numbers in panel A. The representative graphs of three reproducible experiments are shown.