Figure 1.

A relative quantitative polymerase chain reaction assay was performed to measure the mRNA levels of the NTRK1-3 tyrosine kinase domain in the three cell lines (left) and tumor and normal tissues from large-cell neuroendocrine carcinoma (LCNEC) (right). (A) The KM12 cell line exhibited high NTRK1 mRNA levels, whereas H460 cells exhibited intermediate expression. (B and C) There was no increase in the mRNA levels for NTRK2 and NTRK3 in any of the cell lines. (A–C) The H810 cell line showed relatively low NTRK1-3 mRNA levels. (D) Four primary patient samples of LCNEC were resected at our institution; however, we did not observe evidence of increased mRNA levels in the tumor cells compared to those in normal tissue. t1–4, tumor tissues from LCNEC samples; n1–4, normal tissues from the LCNEC samples. NTRK, neurotrophic tyrosine kinase receptor.