CDC7/DBF4 complex of human CDC7, also known as HsCDC7 and Hsk 1, GenBank Accession No. NM_003503 a.a. 1-574(end) with N-terminal GST-tag and MW= 94 kDa, and human DBF4, also known as ASK and CHIF, GenBank Accession No. NM_006716, a.a. 1-674(end) with N-terminal GST-tag and MW= 125 kDa, co-expressed expressed in an Sf9 infected baculovirus expression system.