The cytokine genes human mip-1α (humip-1α), murine mip-1α (mmip-1α), human gm-csf (hugm-csf) and murine mgm-csf (mgm-csf) were modified in silico with respect to codon usage and CpG amount, synthesized via stepwise PCR from oligonucleotides (GeneArt/life technologies) and inserted into the eukaryotic expression vector pcDNA3.1 (+) (Invitrogen). Based on each wild type (wt) gene sequence, three gene variants with varying CpG content were generated. The resulting plasmids were named phuMIP-wt/-11/-0/-43, pmMIP-wt/-13/-0/-42, phuGM-CSF-wt/-12/-0/-63 and pmGM-CSF-wt/-21/-0/-61. The codon adaptation index (CAI) of the gene variants was calculated as described previously (21 (link)). For infection/transfection experiments, mmip-1α gene variants were cloned into the plasmid pPCR-Script Amp SK (+) (Stratagene) using HindIII and EcoRI, resulting in plasmids pT7-mMIP-wt, −0, −13 and −42. For the generation of stable cell lines, mmip-1α variants were inserted into pcDNA5/FRT (Invitrogen) via the restriction sites HindIII and BamHI, resulting in the plasmids pFRT-mMIP-wt, pFRT-mMIP-0, pFRT-mMIP-13 and pFRT-mMIP-42.