Figure 5: Effect on gross tumor volume regression following intratumoral injection of nanoparticle - associated ERBB2 siRNA and p53 plasmid in presence or absence of cisplatin. 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) and/or cisplatin (100 nM), through intratumoral injection and the tumor volumes were estimated according to the modified ellipsoidal formula: 1/2(length × width2).