the present invention provides a means of selectively killing epithelial cell carcinomas by administering a cxcr4 - specific sequence of the gp120 protein or nef proteins or the proteins themselves such as that found in strains hiv - 1 , hiv - 2 , siv , or fiv cxcr4 - specific gp 120 sequences or nef proteins or sequences may be delivered to the mucosa or systemically . the mucosal means of application include oral , intranasal , ocular , intravaginal , rectal , and / or intraurethral administration in liquid or particulate form .