Fig. 1. Integrin α_Vβ₆ recruits HER2 and a trafficking regulatory subnetwork comprising RAB5/RAB7A/GDI2 in HER2+ breast cancer cells.

IAC enrichment coupled with free-label MS was used to define proteins specifically recruited to ligand-bound α_Vβ₆ in HER2+ breast cancer cell lines. (A and B) Volcano plots demonstrating enrichment of proteins identified on LAP (α_Vβ₆ integrin–selective ligand; right) and Coll-I (non-α_Vβ₆ integrin binding ligand; left) matrices in (A) HER2-18 and (B) BT474 cells. Statistical analysis: Fisher’s exact test; quantitative method: weighted spectra; significance level: P < 0.05. Significant proteins (dark gray); nonsignificant proteins (light gray); proteins of interest highlighted in purple. (C and D) Visual representation of ClueGO cellular compartment GO analyses of proteins significantly enriched on LAP in comparison with Coll-I in (C) HER2-18 and (D) BT474 cells. Colors represent specific merged GO term groups, node size represents level of significance of each GO term, and clustering and edge length represent functionally grouped networks based on kappa score. Yellow boxes highlight the cytoplasmic vesicle GO term cluster. (E and F) Top functional subnetworks of proteins significantly enriched on LAP in comparison with Coll-I in (E) HER2-18 and (F) BT474 cells, identified using the OH-PIN algorithm. Colors represent the primary cellular compartment GO term associated with each protein as identified in (C) and (D), respectively. Yellow boxes [(Ea) and (Fa)] highlight the clusters of proteins related to GO term cytoplasmic vesicle, in the top functional subnetwork isolated from each cell line. [(Eb) and (Ec)] Second and third most significant subnetworks in HER2-18 cells. (Fb) All proteins in the cytoplasmic vesicle GO term within the primary functional subnetwork in α_Vβ₆ integrin/LAP-enriched IACs in BT474 cells. All MS data represent three independent experiments. See also figs. S1 (HER2-18) and S3 (BT474) and data files S1 and S2.