CD44 suppression attenuates heregulin-induce invasive and migratory signalling in TamR cells. TamR cells were treated with CD44 siRNA prior to treatment with the erbB lilgand, heregulin Î²1 (Hrg). Whilst Hrg promoted phosphorylation of erbB2 and the EGFR and associated downstream signalling pathways in control cells (A) with a resultant gain in TamR cell migration (B), invasion (C) and growth (D), this response was significantly attenuated in cells pre-treated with CD44siRNA. C: control (untreated) cells; L: siRNA transfection lipid alone; NT: non-targeting siRNA; CD44: CD44siRNA. Controls in figures B, C and D represent samples treated with NT siRNA. *p<0.05 vs. untreated control; **p<0.01 vs. Hrg-treated control.