The invention relates to pyrido[2,3-b]pyrazine compounds of formulae (Ia) and (Ib) which have activity to the modulation of misdirected cellular signal transduction processes such as tyrosine kinases, serine/threonine kinases and/or lipid kinases, their preparation and use as medicaments, especially for the treatment of malignant disorders and other disorders based on pathological cell proliferations: