Figure 6: Effect on tumor volume reduction following intratumoral injection of nanoparticle-associated ERBB2 siRNA and p53 plasmid in presence of doxorubicin. 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 doxorubicin (100 nM), through intratumoral injection and the tumor volumes were estimated according to the modified ellipsoidal formula: 1/2 (length × width2).