SELP gel also enhanced virion retention and shRNA-mediated suppression of vascular endothelial growth factor (VEGF) expression in tumor tissues up to 3 weeks post treatment and attenuated Ad-associated hepatotoxicity, suggesting that both alginate and SELP gels can prolong intratumoral retention of virion while attenuating nonspecific shedding to the liver. This evidence concerns the gene SELP and neoplasm.