Hi, I am sampling the transcript abundance for a virus during an infection time-course. At each time-point post-infection (say 0,1,2,4,8 hours) viral RNA is isolated and hybridized to a tiling array. Given the biology of the virus, I cannot assume that at each time- point there are roughly equal numbers of up and down-regulated genes. Which means that I cannot use quantile-quantile normalization to do any interarray array normalization. What other normalization procedures can I use in such a situation? Thanks in advance, Anjan -- =========================================== anjan purkayastha, phd bioinformatics analyst whitehead institute for biomedical research nine cambridge center cambridge, ma 02142 purkayas [at] wi [dot] mit [dot] edu 703.740.6939