You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Vitamin D receptor signaling mechanisms: integrated actions of a well-defined transcription factor. The main physiological actions of the biologically most active metabolite of vitamin D, 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)D(3)), are calcium and phosphorus uptake and transport and thereby controlling bone formation. Other emergent areas of 1α,25(OH)(2)D(3) action are in the control of immune functions, cellular growth and differentiation. All genomic actions of 1α,25(OH)(2)D(3) are mediated by the transcription factor vitamin D receptor (VDR) that has been the subject of intense study since the 1980's. Thus, vitamin D signaling primarily implies the molecular actions of the VDR. In this review, we present different perspectives on the VDR that incorporate its role as transcription factor and member of the nuclear receptor superfamily, its dynamic changes in genome-wide locations and DNA binding modes, its interaction with chromatin components and its primary protein-coding and non-protein coding target genes and finally how these aspects are united in regulatory networks. By comparing the actions of the VDR, a relatively well-understood and characterized protein, with those of other transcription factors, we aim to build a realistic positioning of vitamin D signaling in the context of other intracellular signaling systems.
{"Chemical": ["1\u03b1,25-dihydroxyvitamin D(3)", "Vitamin D", "1\u03b1,25(OH)(2)D(3)", "phosphorus", "calcium", "vitamin D"]}