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: ["RNA", "CellLine", "Protein", "DNA", "CellType"].

Please return the output as a JSON object of the format: {"DNA" : ["TAL1", ...], "RNA": ["mRNAs", ...], "CellLine": ["T cells", ...], "CellType": ["monocytes", ...], "Protein": ["IL-2", ...]}. 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:

Binding of erythroid and non-erythroid nuclear proteins to the silencer of the human epsilon-globin-encoding gene. To clarify the molecular mechanisms involved in the developmental control of hemoglobin-encoding genes we have been studying the expression of these genes in human cells in continuous culture. We have previously reported the presence of a transcriptional control element with the properties of a silencer extending from-392 to-177 bp relative to the cap site of the human epsilon-globin-encoding gene [ Cao et al., Proc. Natl. Acad. Sci. USA 86 (1989) 5306-5309 ]. We also showed that this silencer has stronger inhibitory activity in HeLa cells, as compared to K562 human erythroleukemia cells. Using deletion mutants and cis-cloned synthetic oligodeoxyribonucleotides in transient expression assays, nucleotide sequences responsible for this effect have now been further delimited to 44 bp located from-294 to-251 bp. Gel electrophoresis mobility shift assays and DNaseI footprinting assays demonstrate that these negative regulatory sequences are recognized differently by proteins present in nuclear extracts obtained from HeLa and K562 cells. Two binding proteins are detected in K562 nuclear extracts, while only one is found in extracts from HeLa cells. Possible mechanisms by which these proteins may regulate transcription of the epsilon-globin-encoding gene in erythroid and non-erythroid cells are discussed.
{"CellLine": ["K562 human erythroleukemia cells", "HeLa", "K562 cells", "HeLa cells"], "CellType": ["non - erythroid cells", "human cells", "erythroid and non - erythroid cells", "erythroid"], "DNA": ["silencer", "hemoglobin - encoding genes", "deletion mutants", "genes", "transcriptional control element", "- 392 to - 177 bp", "- 294 to - 251 bp", "human epsilon - globin - encoding gene", "cap site", "epsilon - globin - encoding gene", "these genes"], "Protein": ["Two binding proteins", "erythroid and non - erythroid nuclear proteins", "DNaseI", "these proteins", "proteins", "proteins present in nuclear extracts"], "RNA": []}