Tobin et al. [72] used PEGylated triple-shell CaP nanoparticles to absorb therapeutic siRNA and ultra-low levels of doxorubicin, and found that the nanoparticles could preferentially localize to tumor in vivo, be internalized by tumor cells in an increasing capacity, effectively deliver siRNA to cause significant decrease of XIAP and inhibit the tumor growth effectively. Here, XIAP is linked to neoplasm.