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 29-kDa proteins phosphorylated in thrombin-activated human platelets are forms of the estrogen receptor-related 27-kDa heat shock protein. Thrombin plays a critical role in platelet activation, hemostasis, and thrombosis. Cellular activation by thrombin leads to the phosphorylation of multiple proteins, most of which are unidentified. We have characterized several 29-kDa proteins that are rapidly phosphorylated following exposure of intact human platelets to thrombin. A murine monoclonal antibody raised to an unidentified estrogen receptor-related 29-kDa protein selectively recognized these proteins as well as a more basic, unphosphorylated 27-kDa protein. Cellular activation by thrombin led to a marked shift in the proportion of protein from the 27-kDa unphosphorylated form to the 29-kDa phosphoprotein species. Using this antibody, we isolated and sequenced a human cDNA clone encoding a protein that was identical to the mammalian 27-kDa heat shock protein (HSP27), a protein of uncertain function that is known to be phosphorylated to several forms and to be transcriptionally induced by estrogen. The 29-kDa proteins were confirmed to be phosphorylated forms of HSP27 by immunoprecipitation studies. Thus, the " estrogen receptor-related protein " is HSP27, and the three major 29-kDa proteins phosphorylated in thrombin-activated platelets are forms of HSP27. These data suggest a role for HSP27 in the signal transduction events of platelet activation.
{"CellLine": ["thrombin - activated platelets", "thrombin - activated human platelets"], "CellType": ["platelet", "thrombin - activated platelets", "intact human platelets"], "DNA": ["cDNA clone"], "Protein": ["29 - kDa phosphoprotein species", "27 - kDa unphosphorylated form", "HSP27", "the 27 - kDa unphosphorylated form", "unidentified estrogen receptor - related 29 - kDa protein", "thrombin", "29 - kDa proteins", "mammalian 27 - kDa heat shock protein", "Thrombin", "estrogen receptor", "estrogen receptor - related 27 - kDa heat shock protein", "unphosphorylated 27 - kDa protein", "estrogen", "multiple proteins", "murine monoclonal antibody"], "RNA": []}