Improvements in our understanding of the intrinsic aberrancies in cancer cells have enabled the design and development of novel therapeutics that specifically target these changes. Among the many complex cellular pathways and mechanisms which have been unveiled by new molecular techniques, RAS-mediated signal transduction is one met with tremendous research interests. Activation of RAS initiates several signaling cascades, of which the RAS-RAF-MEK-ERK pathway is among the better delineated, and is the main focus of this review. Other cellular consequences of RAS activation including interactions with the RHO-family proteins, the PI3-kinase pathway, and other mitogen activated protein kinase cascades, will be discussed. The intricate balance and coordination of multiple RAS-mediated signals lead to ultimate effects on cell growth, differentiation, cycling and survival. Pharmacological strategies such as analog development, synthesis of small molecule inhibitors, antisense technology, and vaccine therapy have been utilized to intervene with key RAS-signaling proteins, in an attempt to provide rational therapeutic solutions in malignant diseases.