MUC5AC and cancer: In the same cancer, CD44 was targeted directly by ON-TARGET plus human CD44 siRNA or indirectly by silencing mucin (MUC5AC) gene expression using a small hairpin RNA construct (pSUPER-Retro-shMUC5AC), resulting in decreased expression of CD44 cell migratory and invasion downstream signalling molecules, such as phosphorylated Src, AKT and integrin-β4 [229].