5T4 Regulates CXCR4 Chemotaxis Figure 6. The transmembrane domain of 5T4 is necessary for CXCR4 cell surface expression. (A), 5T4KO MEF were transduced with retroviral vectors encoding both eGFP and full length or truncated 5T4 or chimeric 5T4/CD44 constructs. Successful infection was assessed by GFP PLoS ONE | www.plosone.org 10 April 2010 | Volume 5 | Issue 4 | e9982