MMP9 and cervical carcinoma: Seven copies of each sequence element originating from the human MMP9 promoter (AP-MMP9), from the URR of HPV18 (AP18), from the URR of CRPV (dAP-CRPV, pAP-CRPV) and from the CRE element were cloned upstream of the luciferase gene (Fig 1A) into the vector pLuc-MCS (Stratagene Corp. La Jolla, CA) and co-transfected with wild-type (wt) CRPV E2 in HPV-negative cervical carcinoma C33A cells (ATCC).