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: ["Gene"].

Please return the output as a JSON object of the format: {"Gene": ["SSX", ...]}. 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:

Isolation and characterization of a structural homologue of human PRK2 from rat liver. Distinguishing substrate and lipid activator specificities. A homologue of human protein kinase C (PKC)-related kinase-2, PRK2, which had previously escaped identification in normal mammalian tissues, was isolated from rat liver as the protease-activated kinase (PAK) originally named PAK-2. The 130-kDa cytosolic enzyme was purified to homogeneity and shown by tryptic peptide and reverse transcriptase- polymerase chain reaction (RT-PCR)-amplified rat cDNA sequence analyses to be structurally related to the 116-kDa rat hepatic PAK-1/protein kinase N (PKN) and, even more closely (95% sequence identity) to the 130-kDa human PKC-related kinase, PRK2. Rat myeloma RNA was used as the RT-PCR template because of its relative abundance in PAK-2/PRK2 mRNA compared with liver and other rat tissues. The catalytic properties of PAK-2/PRK2 in many respects resembled those of hepatic PAK-1/PKN, but were distinguished by more favorable kinetics with several peptide substrates, and greater sensitivity to PKC pseudosubstrate and polybasic amino acid inhibitors. PAK-2/PRK2 was also activated by lipids, particularly cardiolipin and to a lesser extent by other acidic phospholipids and unsaturated fatty acids. Cardiolipin activation was most evident with autophosphorylation and histone H2B phosphorylation, but only marginally evident with the favored ribosomal S6-(229-239) peptide substrate for the protease-activated kinase activity. It was concluded that PAK-2 is the rat homologue of human PRK2, with biochemical properties distinct from although overlapping those of the PAK-1/PKN/PRK1 isoform.
{"Gene": ["PRK2", "PRK1", "protein kinase N", "PAK-1", "PKC", "130-kDa human PKC-related kinase", "PAK", "protein kinase C (PKC)-related kinase-2", "PAK-2", "PKN", "protease-activated kinase"]}