Use of L-nucleic acid (I) as an intracellular active substance. Independent claims are included for: (1) a procedure for binding an intracellular receptor comprising providing a cell containing at least one intracellular receptor； providing (I)； and incubating the cell with (I)； (2) a composition comprising (I) and a discharge vehicle； (3) a high mobility group-A (HMGA) binding nucleic acid, comprising a section box A1 and a section box A2, where the section box A1 and A2 are connected together by intermediate section, and particularly comprises GGGCG, GGGUG or GGGAG； (4) a procedure to screen a HMGA-antagonist or HMGA-agonist comprising either providing a candidate-HMGA-antagonist and/or a candidate HMGA-agonist, providing a nucleic acid； providing a test system, which delivers a signal in the presence of HMGA-antagonist and/or HMGA-agonist, and determining whether the candidate-HMGA-antagonist and/or HMGA-agonist； or providing a phase, particularly solid phase immobilized HMGA, providing nucleic acid, introducing a candidate-HMGA-agonist and/or HMGA-antagonist, and determining； (5) a kit to proof HMGA, comprises the nucleic acid； (6) a HMGA-antagonist and HMGA-agonist, are obtained by the process； (7) a complex comprises a HMGA protein and the nucleic acid； and (8) a nucleic acid binding to a transcriptions factor comprises an AT-hooks. ACTIVITY : Cytostatic； Virucide； Antiarteriosclerotic； Antiinflammatory. MECHANISM OF ACTION : High mobility group-A (HMGA) antagonist； HMGA-agonist. The affinity of (I) to bind with HMGA was tested using biological assays. The results showed that (I) exhibited a median inhibitory concentration (IC 5 0) value of 15 nM.
