ITPR1 and chronic kidney disease: In addition, the repletion of 25(OH)D3 significantly decreased the expression of upregulated genes (Csrp3, Cyfip2, Myl2) and increased the expression of downregulated genes (Atf3, Fos, Itpr1) relative to repletion of 1,25(OH)2D3 in CKD mice.