The ascomycete Trichoderma reesei is an industrial producer of cellulolytic and hemicellulolytic enzymes and also serves as a model for investigations on these enzymes and their genes. The strain QM9978 has a cellulase negative phenotype and therefore presents a valuable tool for understanding the mechanisms underlying cellulase regulation. A transcriptomic analyses of the cellulase negative strain QM9978 and the original strain QM6a have been performed to identify the genetic differences between QM6a and QM9978 leading to the cellulase-negative phenotype Overall design: Two strains were used: T. reesei QM6a (ATCC13631) and QM9978 (Torigoi, E. et al. Mutants of Trichoderma reesei are defective in cellulose induction, but not basal expression of cellulase-encoding genes. Gene 173, 199-203 (1996)) with two time points for each strain T0h (glucose starvation), T24h and T48h (after lactose pulse). All samples are in duplicate.