Compounds of formula (IA) or (IB) are inhibitors of IkB kinase (IKK) activity, and are useful in the treatment of autoimmune and inflammatory diseases: Formula (A) and (B) wherein R.sub.7 is hydrogen or optionally substituted (C.sub.1-C.sub.6)alkyl; ring A is an optionally substituted aryl or heteroaryl ring of 5-13 ring atoms; Z is (a) a radical of formula R.sub.1R.sub.2CHNH--Y-L.sup.1-X.sup.1--(CH.sub.2).sub.z-- wherein: z is 0 or 1; R1 is a carboxylic acid group (--COOH), or an ester group which is hydrolysable by one or more intracellular esterase enzymes to a carboxylic acid group; R2 is the side chain of a natural or non-natural alpha amino acid; Y is a bond, --C(.dbd.O)--, --S(.dbd.P)2-, --C(.dbd.O)O--, --C(.dbd.O)NR3-, --C(.dbd.S)--NR.sub.3, --C(.dbd.NH)--NR.sub.3 or --S(.dbd.O).sub.2NR.sub.3-- wherein R.sub.3 is hydrogen or optionally substituted C.sub.1-C.sub.6 alkyl; L is a divalent linker radical of formula -(Alk.sup.1).sub.m(Q)(Alk.sup.2).sub.p- wherein m, n, p, Q, AIk.sup.1 and AIk.sup.2 are as defined in the claims. ##STR00001##