PDIA4 and myopathy: We find that the levels of a set of ER chaperones, GRP94, GRP78, calnexin and calreticulin, but not ERp72, are increased and these proteins are multifocally accumulated in GNE myopathy muscle fibers, where they co-localize with AβPP, GRP78 and GRP94 form an endoplasmic reticulum chaperoning network with a set of endoplasmic reticulum molecular chaperones processing the unfolded protein substrates [23], [24], and the calnexin/calreticulin system recognize the nascent protein with monoglucosylated N-linked glycans for the subsequent folding and assembly steps.