Loss of the β1,6-GlcNAc-transferase GCNT2 that synthesizes the I antigen branches of N-acetyllactosamine chains was observed in melanomas, and a knockdown of GCNT2 activated the IGFR1-mediated signaling pathways and Tyr phosphorylation upon IGF1 induction in melanoma cells. Here, IGF1 is linked to melanoma.