Activated ERK1/2 increases CD44 in glomerular parietal epithelial cells leading to matrix expansion.

The glycoprotein CD44 is barely detected in normal mouse and human glomeruli, but is increased in glomerular parietal epithelial cells following podocyte injury in focal segmental glomerulosclerosis (FSGS). To determine the biological role and regulation of CD44 in these cells, we employed an in vivo and in vitro approach. Experimental FSGS was induced in CD44 knockout and wild-type mice with a cytotoxic podocyte antibody.