Fig. 1. Native ECM differentially increases expression of the differentiation marker apoA-IV in Caco-2 cells. The Caco-2 cells were grown until confluence on plastic or on different native ECM previously secreted and deposited by mesenchymal cells from the intestine (C9; C11; C20) or the muscle (129CB3), or by colon tumour epithelial cells (HT29-MTX; Caco-2 at 12 day post confluence). Composition of these ECMs is described in Table 1. Total RNA was isolated, and the abundance of apoA-IV transcripts was assayed by RNAse Protection Assay, using ß actin mRNA as an internal control. The mRNA ratio of apoA-IV:ß actin (mean±s.e.m. of three independent cultures performed in triplicate) is expressed as a percentage of the value obtained from Caco-2 on plastic. ^* and ^** differ from the control at P<0.05 and P<0.01 (t-test), respectively. Note that LN5-rich ECM deposited from HT29 MTX cells is the most effective ECM to induce apoA-IV expression in Caco-2 cells.