To obtain a suppressor, an add-on that does nothing to make a firearm more lethal, a person has to commit to a process more invasive, time-consuming, and costly than the purchase of an actual firearm.

Rules for making human tumor cells ... P.Targets of oncogenes and tumor suppressors: key for understanding basic mechanisms of carcinogenesis. Biokhimiya 65, 2–27 (2000). Kufe, D.