Isoxazole compositions useful as inhibitors of ERK

A compound of formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• Ht is pyrrol-3-yl having R3 and QR4 substituents;
• A-B is N—O or O—N;
• R1 is hydrogen or —NHR;
• T is a valence bond;
• Q is —C(O)— or —SO2—;
• each R is independently selected from hydrogen or an optionally substituted aliphatic group having one to six carbons;
• R2 is an aryl group substituted with up to three R8 substituents;
• R3 is hydrogen;
• R4 is —R6 or —NHR6;
• each R6 is independently selected from —(CH2)yR7;
• y is 0-6;
• each R7 is an optionally substituted group independently selected from aryl, heteroaryl or heterocyclyl;
• each R8 is independently selected from halogen, —R′, or —OR′;
• wherein each R′ is independently selected from hydrogen, or aliphatic;
• and.