Disclosed are compound of formula (I), wherein each of R1, R2, R3, R4, R5, R6, X1 and X2 is as defined in the description. These compounds are protein kinases inhibitors, especially the inhibitors of Mek, which are useful in the treatment of cancers and inflammation of mammals. Examples of compounds of formula (I) are: 4-fluoro-5-((2-fluoro-4-iodophenyl)amino)-N-(2-hydroxyethoxy)benzo [d]oxazole-6-carboxamide N-(5-((4-bromo-2-chlorophenyl)amino)-4-fluorobenzo[d]oxazol-6-yl)-1-(2,3- dihydroxypropyl)cyclopropane-1-sulfonamide 4-fluoro-5-((2-fluoro-4-iodophenyl)amino)-N -cyclopropylmethyl-benzo[d] [1,2,3]thiadiazol-6-carboxamide
