To test whether endogenously expressed FN is required for the periFN assembly on tumor cells in adherent status, we stably silenced FN expression in adherent rat mammary adenocarcinoma MTF7 cells and mouse Lewis lung cancer LLC cells and examined their FN expressions (Figure 1a for MTF7 cells and Figure 1d for LLC cells) and surface periFN matrices (Figure 1b,c for MTF7 cells and Figure 1e,f for LLC cells). The gene discussed is FN1; the disease is breast adenocarcinoma.