Although most cells have other enzymes that can degrade RNA, either from the 3' or from the 5' end of the RNA, the exosome complex is essential for cell survival. When the expression of exosome proteins is artificially reduced or stopped, for example by RNA interference, growth stops and the cells eventually die. Both the core proteins of the exosome complex, as well as the two main associated proteins, are essential proteins. Bacteria do not have an exosome complex; however, similar functions are performed by a simpler complex that includes the protein PNPase, called the "degradosome".