To define the impact of TrkA signaling in HER2-positive breast cancer cells, we treated SK-BR-3, BT-474, MDA-MB-453 and JIMT-1 cells with the Trk inhibitor GNF-5837 [34,35] and assessed drug sensitivity, impact on viability and downstream cellular signaling (Figure 4). Here, ERBB2 is linked to breast cancer.