CD44 and neoplasm: To determine the genetic signature of the catulin GFP + cells we isolated, and FACS sorted GFP + CD44 + and GFP-CD44 + cells from 3 independent tumors formed after the injection of the MDA-MB-231-Cat-GFP reporter cell line (Fig. 3b) using CD44 as an additional tumor cell marker to increase sort purity.