Morphogenesis of epithelial tissues relies on the precise developmental control of cell polarity and architecture. In the early Drosophila embryo, the primary epithelium forms during cellularisation, following a tightly controlled genetic programme where specific sets of genes are up-regulated. Some of them, for instance, control membrane invagination between the nuclei anchored at the apical surface of the syncytium. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Overall design: renal collecting duct epitheliao cell line of different genotypes were selected for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain different expression profiles between WT Pkd2 knockout cells.