Treatment and prevention of physiological and pathophysiological state mediated by signal transduction pathway selected from rat sarcoma-rapid accelerated fibrosarcoma-mitogen activated protein kinase-extracellualr signal-regulated kinase signal transduction pathway, phosphoinositol 3-kinase-Akt signal transduction pathway and stress-activated protein kinase signal transduction pathway comprises administering a pyridopyrazine derivative (I). Treatment or prevention of physiological and/or pathophysiological state mediated by at least one signal transduction pathway selected from rat sarcoma-rapid accelerated fibrosarcoma-mitogen activated protein kinase-extracellualr signal-regulated kinase signal transduction pathway, the phosphoinositol 3-kinase-Akt signal transduction pathway and the stress-activated protein kinase signal transduction pathway comprises administering a pyridopyrazine derivatives of formula (I). R 1and R 2 : e.g. aryl (optionally substituted by T 1) or heteroaryl (optionally substituted by T 2)； T 1 : e.g. F or heteroaryl； T 2 : e.g. F or NH-alkyl-NH 2； R 3and R 4 : H or NR 9R 10； R 9 : e.g. alkyl or alkyl-heteroaryl (all optionally substituted) or H； R 10 : -C(Y 1)NR 11R 1) 2； Y 1 : O or S； R 11and R 12 : alkyl (optionally substituted by e.g. T 3or SO 2O-alkyl-aryl), cycloalkyl (optionally substituted by e.g. F or aryl), heterocyclyl (optionally substituted by e.g. OH or aryl), aryl (optionally substituted by T 1or S-heterocyclyl), heteroaryl (optionally substituted by T 2) or H, and T 3 : e.g. CO 2H or heteroaryl. Full Definitions are given in the DEFINITIONS (Full Definitions) section. Independent claims are also included for: (1) new pyridopyrazine derivatives (I') selected from 232 compounds as given in the specification e.g. 1-ethyl-3-[3-(3-hydroxy-phenyl)-pyrido[2,3-b]pyrazin-6-yl]-urea； (2) a pharmaceutical composition (C1) comprising compounds (I'), and (3) a kit comprising compounds (I') and active substance. [Image] ACTIVITY : Cytostatic
