Fig. 5

CD44v3 is implicated in the phospho-TrkA-independent activation of RhoA GTPase. Phosphorylation of TrkA was measured in the presence of a scramble peptide or CD44v3 mimetic peptide 4 (P4) in the presence or absence of NGF (A). Schematic representation of the Rho biosensor; (B). AB-FRET measurement of RhoA activation induced by NGF in MDA-MB-231 cells in the presence of a scramble peptide or P4 (C). Phosphorylation of TrkA and downstream Akt in wild-type MDA-MB-231 and MDA-MB-231 cells expressing kinase-dead TrkA, as determined by western blotting (D). Measurement of RhoA activation using the RhoA biosensor by FRET 25 and 45 min after NGF treatment in cells expressing either a scramble peptide (SP) or CD44v3 mimetic peptide 4 (P4). Based on the FRET signal intensity from low to high, the cells were divided into five groups (E, F). Localization of activated RhoA activation in MDA-MB-231 cells expressing kinase-dead TrkA (G, H)