MATN3 and chronic obstructive pulmonary disease: Conversely, the extraction of proteins associated with intracellular protein trafficking were significantly reduced in Matn3 V194D samples (e.g. buffer 1: coatomer subunit beta (COPB2), coatomer subunit delta (COPD) and GTPase Ran) (supplementary material Table S1), which is consistent with the intracellular retention of mutant matrilin-3 (Fig. 3).