RB1 and neuroendocrine neoplasm: AkuNEC cells exhibited strong positivity for neuroendocrine tumor markers, such as neuron specific enolase (NSE), chromogranin A (CGA), cluster of differentiation 56 (neural cell adhesion molecule; CD56/NCAM), and synaptophysin (major synaptic vesicle protein p38; SYN/p38), but not somatostatin receptor (SSTR) and retinoblastoma (RB) protein by immunohistochemical (IHC) staining analysis, similar to the parental cell line (Table 1).