1 Boston Cell Standards Inc, Boston, Massachusetts.
2 Department of Pathology & Laboratory Medicine, University of Saskatchewan and Saskatoon Health Authority, Saskatoon, Saskatchewan, Canada; Canadian Biomarker Quality Assurance, Saskatoon, Saskatchewan, Canada.
3 Department of Pathology, Isala Hospital, Zwolle, the Netherlands.
4 Boston Cell Standards Inc, Boston, Massachusetts. Electronic address: sbogen@bostoncellstandards.com.