NRP1 and neoplasm: As compared to the negative control treated group, NRP1 and NRP2 showed a prominent reduction of cytoplasmic and membranous staining in all tumor tissues of mice treated with PEI/siRNA nanoparticles against NRP1 (from 3 to 1 in the immune reactive score, with a 95% confidence interval of 2.421 to 2.879 in the control and 0.836 to 1.464 in the treatment group) or NRP2 (from 2 to 1 in the immunoreactive score, with a 95% confidence interval of 1.951 to 2.549 in the control group compared to 0.9925 to 1.607 in the treatment group).