Meanwhile, the rat aortic BMP-4 mRNA level increased prominently at the 4th week in the CKD rats (P < 0.01 versus the Nor group) and declined thereafter, although it was still higher than that of the Nor group (P < 0.01 at the 6th and 8th weeks; Figure 6(b)). This evidence concerns the gene BMP4 and chronic kidney disease.