Wang et al. (2010) observed 35% reduction in tumor growth, inhibition of P-gp and mdr1 gene levels in KB-A-1 cells implanted in Balb/c-nu/nu mice targeted by folic acid conjugated antisense oligodeoxynucleotides-hydroxypropyl-chitosan nanoparticles compared to bare antisense oligodeoxynucleotides to overcome tumor drug resistance. This evidence concerns the gene ABCB1 and neoplasm.