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:

Present and future approaches to screening of G-protein-coupled receptors. As G-protein-coupled receptors (GPCRs) mediate a multitude of cellular signal transduction events, affecting more or less all human disease areas, it is, therefore, no surprise that they comprise the largest family of current drug targets. Screening of compounds interacting with GPCRs has developed during the past decade from receptor binding assays, to various functional determination of coupling to G-proteins, and, more recently, G-protein-independent signal transduction events. Additional opportunities have been presented in drug discovery through novel pharmacological properties obtained for receptor dimers and by identification of ligands for orphan GPCRs. Furthermore, high-throughput formats and automation has substantially facilitated and accelerated the screening process providing powerful tools in improving modern drug discovery.
{"Chemical": []}