COL4A1 and diabetic kidney disease: Because diabetic nephropathy is characterized by excessive accumulation of ECM in the glomeruli, we also assessed the effect of glucose on mRNA expression of the two main components of ECM in MC: FN1 and COL4A1, and found increases of FN1 expression at 48 h, 72 h, and 96 h, but not at 24 h.