Fig. 6. Suppression of Sec13 in primary human fibroblasts results in defective collagen secretion and deposition. Primary human dermal fibroblasts were transfected with siRNA duplexes to suppress Sec13 expression for 72 hours. Cells were then processed for immunofluorescence using antibodies to detect type-I collagen and Sec31A. (A) Cells were labelled with antibodies to detect the C-terminal telopeptide of collagen I (LF-67) and Sec31A. Scale bars: 20 µm. (B) Quantification of collagen deposition from three independent experiments shows a significant reduction (P<0.001) in deposition of fibrillar collagen. Supplementary material Fig. S2 shows further detail and example images from this quantification. (C) Immunoblotting was used to verify suppression of Sec13 and concomitant loss of Sec31A in primary human dermal fibroblasts. Asterisks denote non-specific bands detected with the anti-Sec13 antibody; tubulin was included as a loading control. Molecular-mass markers are shown in kDa.