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:

A thymus-specific member of the HMG protein family regulates the human T cell receptor C alpha enhancer. The human T cell-specific transcription factor TCF-1 alpha plays a key role in the tissue-specific activation of the T cell receptor (TCR) C alpha enhancer and binds to pyrimidine-rich elements (5'-PyCTTTG-3') present in a variety of other T cell-specific control regions. Using amino acid sequence information derived from the DNA affinity-purified protein, we have now isolated cDNA clones encoding TCF-1 alpha. The TCF-1 alpha cDNA contains a single 68-amino-acid domain that is homologous to a region conserved among high-mobility group (HMG) and nonhistone chromosomal proteins. Expression of full-length and mutant cDNA clones in bacteria reveal that the single HMG motif, which is predicted to contain two extended alpha-helical segments, is sufficient to direct the sequence-specific binding of TCF-1 alpha to DNA. Northern blot experiments demonstrate further that TCF-1 alpha mRNA is highly tissue specific, found primarily in the thymus or T cell lines. The immature CEM T cell line expresses relatively low levels of TCF-1 alpha mRNA, which are increased upon activation of these cells by phorbol esters. Interestingly, the cloned TCF-1 alpha protein is a potent transcriptional activator of the human TCR alpha enhancer in nonlymphoid cell lines, whereas the activity of the endogenous protein in T cell lines is strongly dependent on an additional T cell-specific protein that interacts with the core enhancer. TCF-1 alpha is currently unique among the newly emerging family of DNA-binding regulatory proteins that share the HMG motif in that it is a highly tissue-specific RNA polymerase II transcription factor.
{"CellLine": ["thymus or T cell lines", "T cell lines", "nonlymphoid cell lines", "immature CEM T cell line", "T cell - specific protein"], "CellType": [], "DNA": ["full - length", "mutant cDNA clones", "T cell - specific control regions", "cDNA clones", "TCF - 1 alpha cDNA", "core enhancer", "pyrimidine - rich elements", "human TCR alpha enhancer", "human T cell receptor C alpha enhancer", "DNA"], "Protein": ["single HMG motif", "amino acid sequence", "alpha - helical segments", "highly tissue - specific RNA polymerase II", "TCR", "DNA - binding regulatory proteins", "high - mobility group (HMG)", "human T cell receptor C alpha", "thymus - specific member", "68 - amino - acid domain", "endogenous protein", "HMG", "nonhistone chromosomal proteins", "human T cell - specific transcription factor", "TCF - 1 alpha protein", "transcriptional activator", "high - mobility group", "TCF - 1 alpha", "T cell receptor", "HMG motif", "DNA affinity - purified protein", "transcription factor", "HMG protein family"], "RNA": ["TCF - 1 alpha mRNA"]}