There's a signal transduction pathway where a mitogen activated protein (MAP) is phosphorylated by a MAP kinase, which itself is phosphorylated by a MAP kinase

There's a signal transduction pathway where a mitogen activated protein (MAP) is phosphorylated by a MAP kinase, which itself is phosphorylated by a MAP kinase kinase, which is phosphorylated by a MAP kinase kinase kinase, which is phosphorylated by (you guessed it) a MAP kinase kinase kinase kinase. One of my personal favorite protein names is Mothers Against Decapentaplegic. As with most of the funny gene names it was coined by drosophila researchers.