Scheme of the distinct proteasome-types present in murine and human pluripotent and differentiated cells. (A) An abundance of 30S proteasome is presented in mouse embryonic stem cells (mESCs) compared with 3-day differentiated ESCs. The PA28 complex is induced upon differentiation and anchored to the inducible proteasome complex. (B) Downregulated expression of the 30S complex upon neural progenitor cells (NPCs) and neuronal differentiation is found. In contrast to the human ESCs (hESCs), the neural cells have more free 20S complex. AGE, advanced glycation end product; iP, immunoproteasome; RP, regulatory particle.