Quantum dot-mediated siRNA delivery in cancer cells resulted in 50–85% gene knockdown, 30–80% tumor growth inhibition, and up to 4-fold increased cytotoxicity in combination therapies, primarily through targeted gene silencing (e.g., Survivin, TERT, HIF-1α, Bcl-2) and enhanced apoptosis [109]. Here, HIF1A is linked to cancer.