MKI67 and lung neuroendocrine neoplasm: Arbiser et al. [14] studied 20 neuroendocrine lung tumors (5 TCs, 5 ACs, 5 LCNEC, and 5 SCC) in order to determine whether angiogenesis and proliferation rate (assessed by manually counting the number of Ki-67 positive cells in 1000 cells) correlate with tumor types.