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:

Characterization of a novel T lymphocyte protein which binds to a site related to steroid / thyroid hormone receptor response elements in the negative regulatory sequence of the human immunodeficiency virus long terminal repeat. We have previously identified a T lymphocyte protein which binds to a site within the LTR of the human immunodeficiency virus type 1 (HIV-1) and exerts an inhibitory effect on virus gene expression. The palindromic site (site B) recognized by this protein is related to the palindromic binding sites of members of the steroid / thyroid hormone receptor family. Here we characterize the T cell protein binding to this site as a 100 kD protein which is most abundant in T cells and which binds to site B as a 200 kD complex. This protein is distinct from other members of the steroid / thyroid hormone receptor family including the COUP protein which has a closely related DNA binding specificity.
{"CellLine": [], "CellType": ["T cells"], "DNA": ["LTR", "palindromic site", "steroid / thyroid hormone receptor response elements", "negative regulatory sequence", "palindromic binding sites", "site B", "human immunodeficiency virus long terminal repeat"], "Protein": ["novel T lymphocyte protein", "T cell protein", "200 kD complex", "steroid / thyroid hormone receptor family", "T lymphocyte protein", "COUP protein"], "RNA": []}