A method for recombinantly producing a polypeptide in a CHO cell, comprising the step of cultivating a CHO cell which comprises a nucleic acid encoding the polypeptide, and recovering the polypeptide from the CHO cell or the cultivation medium, wherein each of the amino acid residues of the polypeptide is encoded by at least one codon, whereby the codon(s) encoding the same amino acid residue are combined in one group and each of the codons in a group is defined by a specific usage frequency within the group, which is the frequency with which a single codon of a group of codons can be found in a nucleic acid encoding a polypeptide in relation to all codons of one group, whereby the sum of the specific usage frequencies of all codons in one group is 100 %, wherein the overall usage frequency of each codon in the genome of the cell is about the same as its specific usage frequency within its group, wherein the usage frequency of a codon in the polypeptide encoding nucleic acid is about the same as its specific usage frequency within its group, wherein the amino acid codon motif for alanine is selected from SEQ ID NO: 64, 65, 66, 67 and 68, and/or arginine is selected from SEQ ID NO: 69 and 70, and/or asparagine is selected from SEQ ID NO: 71 and 72, and/or aspartic acid is selected from SEQ ID NO: 73 and 74, and/or, cysteine is selected from SEQ ID NO: 75 and 76, and/or glutamine is selected from SEQ ID NO: 77, 78, 79, and 80, and/or glutamic acid is selected from SEQ ID NO: 81 and 82, and/or glycine is selected from SEQ ID NO: 83 and 84, and/or histidine is selected from SEQ ID NO: 85 and 86, and/or isoleucine is selected from SEQ ID NO: 87 and 88, and/or leucine is selected from SEQ ID NO: 89, 90 and 91, and/or lysine is selected from SEQ ID NO: 92 and 93, and/or phenylalanine is selected from SEQ ID NO: 94 and 95, and/or proline is selected from SEQ ID NO: 96 and 97, and/or serine is selected from, SEQ ID NO: 98, 99 and 100, and/or threonine is selected from SEQ ID NO: 101, 102 and 103, and/or tyrosine is selected from SEQ ID NO: 104 and 105, and/or valine is selected from SEQ ID NO: 106, 107 and 108. wherein each of the amino acid residues of the polypeptide is encoded by at least one codon, whereby the codon(s) encoding the same amino acid residue are combined in one group and each of the codons in a group is defined by a specific usage frequency within the group, which is the frequency with which a single codon of a group of codons can be found in a nucleic acid encoding a polypeptide in relation to all codons of one group, whereby the sum of the specific usage frequencies of all codons in one group is 100 %, wherein the overall usage frequency of each codon in the genome of the cell is about the same as its specific usage frequency within its group, wherein the usage frequency of a codon in the polypeptide encoding nucleic acid is about the same as its specific usage frequency within its group, alanine is selected from SEQ ID NO: 64, 65, 66, 67 and 68, and/or arginine is selected from SEQ ID NO: 69 and 70, and/or asparagine is selected from SEQ ID NO: 71 and 72, and/or aspartic acid is selected from SEQ ID NO: 73 and 74, and/or, cysteine is selected from SEQ ID NO: 75 and 76, and/or glutamine is selected from SEQ ID NO: 77, 78, 79, and 80, and/or glutamic acid is selected from SEQ ID NO: 81 and 82, and/or glycine is selected from SEQ ID NO: 83 and 84, and/or histidine is selected from SEQ ID NO: 85 and 86, and/or isoleucine is selected from SEQ ID NO: 87 and 88, and/or leucine is selected from SEQ ID NO: 89, 90 and 91, and/or lysine is selected from SEQ ID NO: 92 and 93, and/or phenylalanine is selected from SEQ ID NO: 94 and 95, and/or proline is selected from SEQ ID NO: 96 and 97, and/or serine is selected from, SEQ ID NO: 98, 99 and 100, and/or threonine is selected from SEQ ID NO: 101, 102 and 103, and/or tyrosine is selected from SEQ ID NO: 104 and 105, and/or valine is selected from SEQ ID NO: 106, 107 and 108.