rSAP is a very robust enzyme and it is rare for dephosphorylation not to proceed essentially to completion. The following transformation controls can be used to diagnose this problem: Uncut vector: to check cell competency and antibiotic resistance. Vector cut and not ligated: to check for uncut vector. Gel purification may be required to remove the last 0.1% of uncut vector. Vector cut and ligated: to check for intact ends and ligation conditions. Vector cut, dephosphorylated and ligated: to check for dephosphorylation. Total colony number should be <5% of the vector cut and ligated.