In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.

Input: Consider Input: Mammalian genomes are extensively transcribed outside the borders of protein-coding genes. Genome-wide studies recently demonstrated that cis-regulatory genomic elements implicated in transcriptional control, such as enhancers and locus-control regions, represent major sites of extragenic noncoding transcription. Enhancer-templated transcripts provide a quantitatively small contribution to the total amount of cellular nonribosomal RNA; nevertheless, the possibility that enhancer transcription and the resulting enhancer RNAs may, in some cases, have functional roles, rather than represent mere transcriptional noise at accessible genomic regions, is supported by an increasing amount of experimental data. In this article we review the current knowledge on enhancer transcription and its functional implications.

Output: Noncoding transcription at enhancers: general principles and functional models.

Input: Consider Input: P19 cells are a line of pluripotent embryonal carcinoma able to grow continuously in serum-supplemented media. The differentiation of these cells can be controlled by nontoxic drugs. Retinoic acid effectively induces the development of neurons, astroglia and microglia--cell types normally derived from the neuroectoderm. Aggregates of P19 cells exposed to dimethyl sulfoxide differentiate into endodermal and mesodermal derivatives including cardiac and skeletal muscle. P19 cells can be effectively transfected with DNA encoding recombinant genes and stable lines expressing these genes can be readily isolated. These manipulations make P19 cells suitable material for investigating the molecular mechanisms governing developmental decision made by differentiating pluripotent cells.

Output: P19 embryonal carcinoma cells.

Input: Consider Input: Procedures are described for the isolation of lipoproteins from human serum by precipitation with polyanions and divalent cations. A mixture of low and very low density lipoproteins can be prepared without ultracentrifugation by precipitation with heparin and either MnCl(2) alone or MgCl(2) plus sucrose. In both cases the precipitation is reversible, selective, and complete. The highly concentrated isolated lipoproteins are free of other plasma proteins as judged by immunological and electrophoretic methods. The low density and very low density lipoproteins can then be separated from each other by ultracentrifugation. The advantage of the method is that large amounts of lipoproteins can be prepared with only a single preparative ultracentrifugation. Polyanions other than heparin may also be used; when the precipitation of the low and very low density lipoproteins is achieved with dextran sulfate and MnCl(2), or sodium phosphotungstate and MgCl(2), the high density lipoproteins can subsequently be precipitated by increasing the concentrations of the reagents. These lipoproteins, containing small amounts of protein contaminants, are further purified by ultracentrifugation at d 1.22. With a single preparative ultracentrifugation, immunologically pure high density lipoproteins can be isolated from large volumes of serum.
Output: Rapid method for the isolation of lipoproteins from human serum by precipitation with polyanions.