A set of genetic constructs comprising: a) Construct (i) encoded by a nucleic acid molecule, which comprises at least the following components: A1 - A2 - A3 - A4 - A5 (i) wherein A1 is a first promoter; A2 is a first homologous portion; A3 is a meganuclease cleavage site; A4 is a first marker gene; A5 is a second homologous portion; and wherein construct (i) is configured to be stably integrated into the genome of at least one target cell; b) Construct (ii) encoded by a nucleic acid molecule, which comprises at least the following components: A2' - B1- B2 - B3 - B4 - A5' (ii) wherein A2' comprises a portion of said first homologous portion A2; B1 is a second marker gene different to said first marker gene; B2 is a second promoter; B3 is a multiple cloning site; B4 is a third promoter; A5' comprises a portion of said second homologous portion A5; c) At least one construct selected from the group comprising, constructs (iii) or (iv) encoded by nucleic acid molecules, which comprise at least the following components: C1 - C2 (iii); C3 (iv); or Construct (v) which is an isolated or recombinant protein which comprises at least the following component: C4 (v); wherein C1 is a fourth promoter; C2 is the open reading frame of a meganuclease; C3 are messenger RNA (mRNA) versions of said meganuclease; C4 is an isolated or recombinant protein of said meganuclease; wherein said meganuclease from constructs (iii), (iv) or (v) recognize and cleave A3; and wherein constructs (iii), (iv) or (v) are configured to be co-transfected with construct (ii) into said at least one target cell; wherein said components of each of said constructs (i), (ii), and (iii) are selected from the groups comprising: Component Group A1 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) A2 EF1α intron 1 complete sequence, 5' homology (SEQ ID NO: 3) A2' EF1α intron 1 short sequence, 5' homology (SEQ ID NO: 29) A4 Hygromycin resistance gene (SEQ ID NO: 2); Neomycin resistance gene (SEQ ID NO: 7); Puromycin resistance gene (SEQ ID NO: 21); A5 Neomycin resistance gene (SEQ ID NO: 7) A5' Inactive neomycin resistance gene deleted of its 3' end, 3' homology (SEQ ID NO: 13) B 1 Hygromycin resistance gene (SEQ ID NO: 2); Neomycin resistance gene (SEQ ID NO: 7); Puromycin resistance gene (SEQ ID NO: 21); B2 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) B4 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) C1 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52). a) Construct (i) encoded by a nucleic acid molecule, which comprises at least the following components: A1 - A2 - A3 - A4 - A5 (i) wherein A1 is a first promoter; A2 is a first homologous portion; A3 is a meganuclease cleavage site; A4 is a first marker gene; A5 is a second homologous portion; and wherein construct (i) is configured to be stably integrated into the genome of at least one target cell; b) Construct (ii) encoded by a nucleic acid molecule, which comprises at least the following components: A2' - B1- B2 - B3 - B4 - A5' (ii) wherein A2' comprises a portion of said first homologous portion A2; B1 is a second marker gene different to said first marker gene; B2 is a second promoter; B3 is a multiple cloning site; B4 is a third promoter; A5' comprises a portion of said second homologous portion A5; c) At least one construct selected from the group comprising, constructs (iii) or (iv) encoded by nucleic acid molecules, which comprise at least the following components: C1 - C2 (iii); C3 (iv); or Construct (v) which is an isolated or recombinant protein which comprises at least the following component: C4 (v); wherein C1 is a fourth promoter; C2 is the open reading frame of a meganuclease; C3 are messenger RNA (mRNA) versions of said meganuclease; C4 is an isolated or recombinant protein of said meganuclease; wherein said meganuclease from constructs (iii), (iv) or (v) recognize and cleave A3; and wherein constructs (iii), (iv) or (v) are configured to be co-transfected with construct (ii) into said at least one target cell; wherein said components of each of said constructs (i), (ii), and (iii) are selected from the groups comprising: Component Group A1 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) A2 EF1α intron 1 complete sequence, 5' homology (SEQ ID NO: 3) A2' EF1α intron 1 short sequence, 5' homology (SEQ ID NO: 29) A4 Hygromycin resistance gene (SEQ ID NO: 2); Neomycin resistance gene (SEQ ID NO: 7); Puromycin resistance gene (SEQ ID NO: 21); A5 Neomycin resistance gene (SEQ ID NO: 7) A5' Inactive neomycin resistance gene deleted of its 3' end, 3' homology (SEQ ID NO: 13) B 1 Hygromycin resistance gene (SEQ ID NO: 2); Neomycin resistance gene (SEQ ID NO: 7); Puromycin resistance gene (SEQ ID NO: 21); B2 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) B4 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52) C1 pEF1α promoter (SEQ ID NO: 1); pSV40 (SEQ ID NO: 20); pCMV (SEQ ID NO: 25); Ubiquitin sub-unit c promoter (SEQ ID NO: 52).