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:

TCF-1, a T cell-specific transcription factor of the HMG box family, interacts with sequence motifs in the TCR beta and TCR delta enhancers. We have recently identified and cloned TCF-1, a T cell-specific transcription factor with specificity for the AACAAAG motif in the CD3 epsilon enhancer and for the TTCAAAG motif in the TCR alpha enhancer. TCF-1 belongs to the family of transcription-regulating proteins which share a region of homology termed the HMG-box. Here, we show by gel retardation analysis that TCF-1 specifically recognizes the T beta 5 element of the TCR beta enhancer and the T delta 7 element of the TCR delta enhancer. Comparison of the sequences of all elements recognized by TCF-1 defines a consensus motif A / T A / T C A A / G A G. These observations imply that TCF-1 is involved in the control of several T cell-specific genes and might thus play an important role in the establishment and maintenance of the mature T cell phenotype.
{"CellLine": [], "CellType": ["mature T cell phenotype"], "DNA": ["consensus motif", "TCR beta enhancer", "TCR alpha enhancer", "T cell - specific genes", "CD3 epsilon enhancer", "sequence motifs", "TCR beta and TCR delta enhancers", "A / T A / T C A A / G A G", "T beta 5 element", "elements", "the TCR delta enhancer", "T delta 7 element", "TCR delta enhancer", "TTCAAAG motif"], "Protein": ["T cell - specific transcription factor", "HMG box family", "transcription - regulating proteins", "TCF - 1", "HMG - box"], "RNA": []}