PTK2B and neuroendocrine carcinoma: We observed a significantly higher number of strongly phosphorylated peptides in the GEP-NET cell lines NT-3 and NT-18LM compared to the GEP-NEC cell lines NT-32 and NT-38, i.e., the STK as well as the PTK array revealed increased overall STK and PTK activity in GEP-NET cells (Fig. 3A, Suppl.