Currently Drosophila is a dominant experimental model in developmental biology and in gene regulation in eukaryotes. This volume summarizes some thirty years of experience in the handling of in vitro cultured Drosophila cells. Its main emphasis is on gene transfer methodology, cell responses to heat shock, hormonal regulation of genes, and on the expression and mobility of transposable elements.Key Features* Some thirty years of experience in handling in vitro cultured Drosophila cells* Cell cultures which provide material for a multiplicity of biochemical approaches* DNA-mediated gene transfer as an irreplaceable tool for analyzing basic mechanisms of regulation* Drosophila cell lines which qualify them for use in biotechnology