CASP3 and breast cancer: However, both nanoparticles were internalized by breast cancer cells, with Apo-bLf-loaded silk NPs showing greater internalization compared to void NPs, which resulted in higher cell toxicity, greater caspase-3 release, and better efficacy in reducing the tumor sphere size of Apo-bLf-loaded silk NPs than Fe-bLf-loaded silk NPs.