CD44 and neoplasm: The adenoviral vectors Ad-CD44-N-HIF3α4, Ad-SOCS3, Ad-p53 and Ad-LacZ or PBS were intratumorally injected into the MDA-MB-231 subcutaneous xenograft tumors to examine the in vivo anti-tumor activity of Ad-CD44-N-HIF3α4 in comparison with Ad-SOCS3 and Ad-p53.