Described herein are compounds that are useful as protein kinase inhibitors having the formula: wherein Z1 and Z2 are each independently nitrogen or CH and Ring A, TmR1, QR2, UnR3, and Sp are as described in the specification. The compounds are especially useful as inhibitors of ERK2 and for treating diseases in mammals that are alleviated by a protein kinase inhibitor, particularly diseases such as cancer, inflammatory disorders, restenosis, diabetes, and cardiovascular disease.