Figure 4: Effect on gross tumor volume regression following intratumoral injection of nanoparticle-associated ERBB2 siRNA and p53 plasmid. The mice bearing 4T1-induced mammary tumor were treated with 100 µl of the particle suspension originally formulated in 1 ml of DMEM with 7 mM of Ca2+ in presence or absence of ERBB2 siRNA (800 nM) plus p53 (100 ng) or anticancer drugs (100 nM), through intratumoral injection and the body weight was measured throughout the experiment from day 1 to day 29.