Human MEK1 (K97R) also known as Mitogen-Activated Protein Kinase Kinase 1, MAPK/ERK Kinase 1, ERK Activator Kinase 1, MAPKK 1, and PRKMK, GenBank Accession No. NM_002755, a.a. 1-393(full length) with C-terminal His-tag, expressed in an E. coli expression system. MW=44 kDa