Abstract: The present invention relates to isolated nucleic acid molecules encoding Prolactin Regulatory Element Binding protein (PREB) and recombinant proteins encoded thereby. The nucleic acid sequences are useful in the production of recombinant PREB, as probes, and in the control of gene expression, and in particular, in the control of prolactin gene expression. In particular embodiments of the invention, PREB nucleic acid sequences are used to detect transcripts of the gene in astrocytomas, to detect trisomy and to detect a propensity of a subject to develop osteoporosis. In other embodiments of the invention, the PREB nucleic acid sequences, or the products thereof, are used for preventing or controlling osteoporosis in a subject.

Abstract: A simple technique for the simultaneous measurement of relative levels of a specific mRNA in numberous small samples of biological specimens is described. The technique involves denaturation of cytoplasmic preparations, followed by dotting of up to 96 samples onto a single sheet of nitrocellulose, hybridization with a .sup.32 P-labeled cDNA plasmid, autoradiography, and scanning. By analyzing cytoplasmic preparations instead of purified RNA, manipulations of multiple samples prior to analysis are minimized. Experiments with a clonal line of rat pituitary tumor (GH.sub.3) cells show that this technique can be employed to follow the induction by Ca.sup.2+ of prolactin mRNA sequences, employing cytoplasm prepared from as little as 2.5.times.10.sup.4 cells. The specificity of the technique for prolactin mRNA is shown by employing GC cells, a GH.sub.3 cell variant lacking detectable prolactin mRNA sequences.