Combination comprising one or more nucleic acid molecules, said one or more nucleic acid molecules comprising: (a) a nucleic acid sequence A, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, comprising amino acid substitutions at positions 44 and/or 47 compared to SEQ ID NO: 2, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, wherein the dimerization domain is a homodimerization domain or a heterodimerization domain, preferably selected from the group consisting of ERT2, FKBP, CalcineurinA, CyP-Fas, GyrB, GAI, GID1, Snap-tag, HaloTag, eDHFR and FRB domain of mTOR; and (b) a nucleic acid sequence B, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, comprising amino acid substitutions at positions 4, 5, 37, 63, 77 and/or 79 compared to SEQ ID NO: 4, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, analogously to the localization of the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), said dimerization domain corresponding to the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), wherein the amino acid sequences encoded by nucleic acid A and B do not pair with each other in the absence of a dimerization agent. (a) a nucleic acid sequence A, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, comprising amino acid substitutions at positions 44 and/or 47 compared to SEQ ID NO: 2, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, wherein the dimerization domain is a homodimerization domain or a heterodimerization domain, preferably selected from the group consisting of ERT2, FKBP, CalcineurinA, CyP-Fas, GyrB, GAI, GID1, Snap-tag, HaloTag, eDHFR and FRB domain of mTOR; and (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, comprising amino acid substitutions at positions 44 and/or 47 compared to SEQ ID NO: 2, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, wherein the dimerization domain is a homodimerization domain or a heterodimerization domain, preferably selected from the group consisting of ERT2, FKBP, CalcineurinA, CyP-Fas, GyrB, GAI, GID1, Snap-tag, HaloTag, eDHFR and FRB domain of mTOR; and (b) a nucleic acid sequence B, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, comprising amino acid substitutions at positions 4, 5, 37, 63, 77 and/or 79 compared to SEQ ID NO: 4, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, analogously to the localization of the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), said dimerization domain corresponding to the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, comprising amino acid substitutions at positions 4, 5, 37, 63, 77 and/or 79 compared to SEQ ID NO: 4, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, analogously to the localization of the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), said dimerization domain corresponding to the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i),