You talk resazurin which is the dye behind the assay.
Manufacturer is Biosource, probably
Biosource Technologies, Inc.
3333 Vaca Valley Parkway
Vacaville, CA 95688
Telephone: (707) 446-5501
Fax: (707) 446-3917
Email: Info at biosource-bti.com
Regards
Gerhard.nebe-von-caron at unilever.com