CD44 and lung cancer: Knockdown of CD44 reduced the migration and invasion abilities of lung cancer cells (Fig. 6E); on the other hand, overexpression of HA-CD44, including the short form, HA-CD44st, and standard form, HA-CD44s, increased the migration and invasion abilities of lung cancer cells (Fig. 6F), indicating that Sp1-mediated inhibition of CD44 decreases the metastatic ability of lung cancer cells.