For example, a 5-fold increase in the tumor accumulation of liposomes loaded with daunorubicin was observed in EGFR-positive A431 epidermoid carcinoma cells coexisting with a small fraction of EGFR-negative Balb-3T3 embryonic fibroblasts after pre-treatment with EGFR-targeted photodynamic therapy [31]. The gene discussed is EGFR; the disease is squamous cell carcinoma.