To solve this problem, we amplified the cDNA encoding the CD44 extracellular domain from various breast cancer cells using a pair of primers, forward primer 5′-TATAAGCTTTTCGCTCCGGACACCATGGACAAG-3′, and reverse primer 5′-ATAAGATCT TTCTGGAATTTGGGGTGTCCTTAT-3′. The gene discussed is CD44; the disease is breast cancer.