Among these activators are interleukin-6, which elicited growth-inhibiting effects on LNCaP prostate cancer cells via C/EBPδ activation [51], 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1, 3-propanedione (HMDB), which attenuated the growth of A431 epidermoid carcinoma xenografts in severe combined immunodeficient mice [18,27], and metformin, which induced autophagy of Huh7 liver cancer cells via C/EBPδ activation [52]. This evidence concerns the gene CEBPD and squamous cell carcinoma.