Interestingly, PCI37A-AXLC2 cells did not express more NRG1 compared to vector control despite AXL being overexpressed (Fig. 5A), and cetuximab-resistant PDX tumor (UW-SCC25) did not express NRG1 even though they had AXL expression (Fig. 5B). The gene discussed is NRG1; the disease is neoplasm.