Since primary B-lymphocytes are not suitable for lentivirus infection or transfection with other forms of interfering RNA and to further demonstrate that Syndecan-4 shedding was mediated by MMP-7, cells were treated with recombinant active MMP-7 in the presence or absence of an MMP-7 inhibitor (GM6001). This evidence concerns the gene SDC4 and lentivirus infection.