The quantikine Human cardiotrophln 1 (CT-1) immunoassay is a 4.5 hour solid phase elisa designed to measure Human cardiotrophln 1 (CT-1) levels in cell culture supernates, serum, and plasma. It contains e. Coli-expressed recombinant Human cardiotrophln 1 (CT-1) and antibodies raised against recombinant Human cardiotrophln 1 (CT-1). This immunoassay has been shown to accurately quantitate the recombinant factor. Results obtained using natural Human cardiotrophln 1 (CT-1) showed dose response curves that were parallel to the standard curves obtained using the recombinant quantikine kit standards. These results indicate that this kit can be used to determine relative mass values for natural Human cardiotrophln 1 (CT-1)