5687
Apoptosis is a regulated form of cell death that may be triggered by natural killer ( NK ) or cytotoxic T cells , which effect target cell lysis by cytolytic effector and related proteins through complex intracellular signals .
 cell, natural killer, NK, cytotoxic T cells, cell, intracellular
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 cell, natural killer, NK, cytotoxic T cells, cell, intracellular