Numbers game

Although gigantic basketball player Shaquille O'Neal may dwarf us mortals, his cells are no bigger than yours or mine. He just has more of them. But how vertebrates regulate their cell number has been as puzzling as Shaq's inability to shoot free throws. Now, a team of researchers has pinpointed a gene that helps determine body size in vertebrates by controlling cell division. The findings support the notion that vertebrates govern body size by regulating cell number, whereas insects vary both cell size and cell number.

Andreas Trumpp (Swiss Institute for Experimental Cancer Research, Epalinges, Switzerland) and colleagues focused on c-myc, a proto-oncogene that is mutated or overexpressed in ∼20% of human cancers and was suspected to be a cell division regulator. Recent fly studies had challenged this view, says Trumpp. Reducing the levels of dmyc, the...