As shown in Fig 2a,IGF-1 stimulation resulted in IGF-1R auto-phosphorylation and activation of downstream PI3K/AKT and MEK/ERK signaling pathways in H446 and H526 cells, while SKBR3, a breast cancer cell line known to express low amount of IGF-1R, did not response well. Here, IGF1 is linked to breast cancer.