CASP9 and head and neck cancer: Moreover, gemcitabine (antimetabolite) and doxorubicin (anthracycline) combination therapy was shown to be an effective chemotherapy for some patients with metastatic head and neck cancers [155] via caspase-9/3—dependent mitochondrial cell death by inducing CerS1/C18 ceramide in both in vitro and in vivo xenograft mouse models for head and neck cancers [156].