Abstract
Proteins produced in cultured Drosophila cells during the heat-shock response (HSP) were recently shown by autoradiography to be confined in large measure to the cell nucleus. Nuclear HSP are not associated with nucleosomes solubilized by treatment with staphylococcal nuclease at low ionic strength nor are HSP released by extraction with high salt, which solubilizes most of the remaining histones and DNA. Possible functions of nuclear HSP are discussed.