The a4 chain was not detected in mouse skin. Col6a1 null skin was negative for all novel chains. As dysregulation of the tissue remodelling phase of wound healing results in fibrosis, we also studied the expression of the collagen VI chains in fibrotic skin induced by local bleomycin injection. Here, as in wound healing, the a3 chain was strongly expressed in the fibrotic dermis. However, in contrast to wounds where the a5 chain was absent from blood vessels, this chain was up-regulated in the blood vessels in the fibrotic dermis. As in wounds, the expression of the a6 chain was also up-regulated in in the blood vessels in the fibrotic dermis. The a2 chains from wild type and Col6a1 null mice migrated with the same expected mobility. In contrast, the a3 chain was detected in both uninjured skin and wounds at day 7, but was extensively degraded in unwounded skin of wild type mice and even more so in wounds of wild type and Col6a1 null mice. Immunoblotting revealed a ladder of bands ranging from the fulllength protein to 35 kDa fragments. Interestingly, wound AB1010 extracts contained more a3 chain and a3 chain fragments than extracts of unwounded skin, indicating an increased synthesis or greater solubility of collagen VI in wounds. The SCH772984 side effects extracted material may represent tetramers that have not yet been assembled into fibrils or molecules that are being degraded due to high protein turnover. Also wound extracts from Col6a1 null mice contained more a3 chain, than extracts of unwounded skin. This material probably represents a soluble intracellular pool of a3 chain in the Col6a1 null fibroblasts. The full-length a5 and a6 chains gave only weak bands in immunoblots of extracts of unwounded skin of wild type mice. In wound extracts at day 7 the signals for the full-length chains were stronger, but absent in extracts from Col6a1 null mice except for a weak band for the a5 chain. Collagen VI microfibrils are connected to large collagen fibrils and are thought to regulate their formation. We therefore stained wounds of wild type and Col6a1 null mice with antibodies against collagen I, but the overall distribution of this collagen was similar between genotypes.