ERK1 and ERK2 regulate embryonic stem cell self-renewal through phosphorylation of Klf4

Kruppel-like factor 4 (Klf4) promotes the self-renewal of embryonic stem cells, but how Klf4 itself is regulated is unclear. ERK1 and ERK2 are now found to phosphorylate Klf4, targeting it for degradation via the ubiquitin-proteasome pathway and promoting cellular differentiation.