Thus, two possibilities currently under study in our laboratory is that GM-CSF enhances mucosal immunogenicity of skin-delivered PMED influenza DNA vaccines by increasing the migration of antigen presenting cells bearing skin-derived antigen to mucosal compartments [20] and/or enhances the ability of skin-derived APC to imprint a mucosal homing phenotype on stimulated T cells [60]. The gene discussed is CSF2; the disease is influenza.