Via EurekAlert!, a biomechanism of cellular aging: "Three separate studies confirm a gene that suppresses tumor cell growth also plays a key role in aging. The researchers found increasing concentration, or expression, of the gene p16INK4a in older cells; these aging cells worked poorly compared to young cells and remembered their 'age' even when transferred from old mice to young mice. ... The studies indicate that certain stem cells lose their ability to divide and replace themselves with age as the expression of p16INK4a increases ... even though old mice lacking p16INK4a show enhanced stem cell function, they do not live longer. This is because p16INK4a is an important cancer-suppressor gene, and mice lacking p16INK4a develop more cancers than old, normal mice ... p16INK4a loss was associated with an improvement in some but not all of the consequences of aging." The age-old story: cancer or aging, pick one. Setting forth to repair the accumulation of damage seems like a better plan than tweaking the mechanism for greater performance at this point.