Recombinant protein corresponding to full-length human JNK1a1/SAPK1c with an N-terminal His-tag, expressed in Sf21 cells. Specific Activity: 39u/mg where one Unit of JNK1a1/SPAK1c activity is equal to 1nmol phosphate incorporated into GST-ATF2 per minute. Storage and Stability: Aliquot to avoid repeated freezing and thawing and store at -70C. Aliquots are stable for 6 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.