TEM analysis of HeLa cells treated with DMSO or MG132. Note the layered structures (red arrowheads) in the mitochondrial matrix (ii, iii), budding from mitochondria (iv), attached to mitochondria (v-vi), away from mitochondria (vii) or inside the MAPAs (viii, ix) in MG132-treated cells. Scale bar=500 nm. M, mitochondrion. N, nucleus. 