Figure 1.

Induction of FN matrix assembly in 3D culture does not correlate with changes in secreted FN or surface integrin expression. The assembly of FN into HMWFMs was assessed using a DOC differential solubilization assay, SDS-PAGE under reducing conditions, and immunoblot analysis. (A) FN was detected in the soluble and insoluble fractions of the 3D samples only. (B) Secreted FN by cells in 2D or 3D culture was determined by immunoblotting. Surface expression of α5β1 (C) or of activated β1 integrin (D) was determined by staining with monoclonal mAbs recognizing the α5 integrin subunit or activated β1, respectively. Control cells were incubated in a preimmune IgG to establish baseline mean fluorescence. No significant change in FN secretion or surface integrin expression was detected.