MUSK and cancer: In agreement with previous studies3, a substantial heterogeneity of adaptive responses was observed in lapatinib-resistant cancer cells, including previously described (Axl, MET)2 and novel upregulated pathways, such as NFGR, MUSK, VEGFR1, PDGFRα, PDGFRβ, EPHA2, and EPHB2 (Fig. 1f).