COL1A1 and renal fibrosis: We also demonstrated that siRNA knockdown of TGFβ1 and phosphorylated Smad 3 in normal TM cells, also correlated with an increase in RASAL1 expression and a resultant decrease in expression of COL1A1 and DNMT1 This further demonstrates that there is an inverse correlation between TGFβ1 and RASAL1 expression in trabecular meshwork cells, and that TGFβ1 may play a role in regulating RASAL1 expression as seen in renal fibrosis[57] perhaps in a similar methylation-dependent manner.