p53 operates as a tetramer (4 individual p53 [monomeric] proteins come together to form the active protein complex), and can have a dominant negative effect if

p53 operates as a tetramer (4 individual p53 [monomeric] proteins come together to form the active protein complex), and can have a dominant negative effect if one of the two p53 genes are mutated. This basically means we have two copies of the gene, but if one is mutated and you form a tetramer and 1 or more of the tetramer's monomers are mutants then that tetramer is far less active. Even if you had lots of copies of p53, its effect could still be down-regulated by a single mutant. There's been some work to try and reactivate p53 where it's been knocked out, although I'm not sure how successful it's been. http://www.ejcancer.info/article/S0959-8049(03)00454-4/abstract http://www.ejcancer.info/article/S0959-8049(03)00454-4/abstr...