Raf-1, a protein serine-threonine kinase, plays a critical role in mitogen-activated protein kinase kinase (MKK/MEK)- mitogen-activated protein kinase (extracellular signal-regulated kinase) (MAPK/ERK) pathways. We show here that systemically delivered novel cationic cardiolipin liposomes (NeoPhectin-AT) containing a small interfering RNA (siRNA) against Raf-1 silence the expression of Raf-1 in tumor tissues and inhibit tumor growth in xenograft model of human prostate cancer. The knockdown of Raf-1 expression by siRNA is also associated with down-regulation of cyclin D1 expression in vivo.