Cultured metastatic human prostate cancer cells C4-2B were labeled with 60 nm gold nanoparticles conjugated with C225 anti-EGFR antibodies (EGF receptor is over-expressed by these tumors) and DiI fluorescent dye to provide a label for viability and lineage tracing after transplantation (Figure 18c). Here, EGFR is linked to prostate carcinoma.