Transfection of pcDNA3.1-CCL21 DNA vector can increase CCL21 protein expression in RAW 264.7 cells (macrophage like, Abelson leukemia virus transformed cell line) while intraperitoneal injection of pcDNA3.1-CCL21 can increase the frequencies of CCR7+ PBL in normal mice and BD mice [56]. Here, CCR7 is linked to Behcet disease.