The invention is directed to compounds that are specific inhibitors of PKC delta, and methods and compositions for the treatment and prevention of cancers and other disorders. Compositions comprising compounds of the invention are used to treat cancers such as, for example, carcinoid and neuroendocrine tumors, malignant melanomas, pancreatic, gastrointestinal and lung cancers. Neuroendocrine tumor cell lines of pulmonary and gastrointestinal origin are surprisingly sensitive to PKC delta inhibition by the compounds of the invention. The invention is further directed to methods, compositions and kits containing compounds of the formulas (Ia), (IIa), (IIIa), (IVa), and (V) as disclosed and described in FIGS. 11 and 12.