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:

The promoter of the CD19 gene is a target for the B-cell-specific transcription factor BSAP. The CD19 protein is expressed on the surface of all B-lymphoid cells with the exception of terminally differentiated plasma cells and has been implicated as a signal-transducing receptor in the control of proliferation and differentiation. Here we demonstrate complete correlation between the expression pattern of the CD19 gene and the B-cell-specific transcription factor BSAP in a large panel of B-lymphoid cell lines. The human CD19 gene has been cloned, and several BSAP-binding sites have been mapped by in vitro protein-DNA binding studies. In particular, a high-affinity BSAP-binding site instead of a TATA sequence is located in the-30 promoter region upstream of a cluster of heterogeneous transcription start sites. Moreover, this site is occupied by BSAP in vivo in a CD19-expressing B-cell line but not in plasma or HeLa cells. This high-affinity site has been conserved in the promoters of both human and mouse CD19 genes and was furthermore shown to confer B-cell specificity to a beta-globin reporter gene in transient transfection experiments. In addition, BSAP was found to be the only abundant DNA-binding activity of B-cell nuclear extracts that interacts with the CD19 promoter. Together, this evidence strongly implicates BSAP in the regulation of the CD19 gene.
{"CellLine": ["B - lymphoid cell lines", "B - cell line", "CD19 - expressing B - cell line", "HeLa cells"], "CellType": ["terminally differentiated plasma cells", "B - lymphoid cells", "plasma"], "DNA": ["human CD19 gene", "BSAP - binding sites", "- 30 promoter region", "heterogeneous transcription start sites", "human and mouse CD19 genes", "CD19 gene", "promoter", "TATA sequence", "CD19 promoter", "high - affinity site", "high - affinity BSAP - binding site", "promoters"], "Protein": ["CD19 protein", "BSAP", "B - cell - specific transcription factor"], "RNA": []}