The invention provides a compound for use as a protein kinase B inhibitor, the compound being a compound of the formula (I) or salts, solvates, tautomers or N-oxides thereof, wherein T is N or CR5; J1-J2 is N═C(R6), (R7)C═N, (R8)N—C(O), (R8)2C—C(O), N═N or (R7)C═C(R6); E is a monocyclic carbocyclic or heterocyclic group of 5 or 6 ring members, the heterocyclic group containing up to 3 heteroatoms selected from O, N and S; Q1 is a bond or a saturated C1-3 hydrocarbon linker group, one of the carbon atoms in the linker group being optionally be replaced by an oxygen or nitrogen atom, or an adjacent pair of carbon atoms may be replaced by CONRq or NRqCO where Rq is hydrogen or methyl, or Rq is a C1-4 alkylene chain linked to R1 or a carbon atom of Q1 to form a cyclic moiety; and wherein the carbon atoms of the linker group Q1 may optionally bear one or more substituents selected from fluorine and hydroxy; Q2 is a bond or a saturated hydrocarbon linker group containing from 1 to 3 carbon atoms, wherein one of the carbon atoms in the linker group may optionally be replaced by an oxygen or nitrogen atom; and wherein the carbon atoms of the linker group may optionally bear one or more substituents selected from fluorine and hydroxy, provided that the hydroxy group when present is not located at a carbon atom a with respect to the G group; and provided that when E is aryl or heteroaryl, then Q2 is other than a bond; G is hydrogen, NR2R3, OH or SH provided that when E is aryl or heteroaryl and Q2 is a bond, then G is hydrogen; R1 is hydrogen or an aryl or heteroaryl group, with the proviso that when R1 is hydrogen and G is NR2R3, then Q2 is a bond; and R2, R3, R4, R6 and R8 are as defined in the claims.