HTRA1 and endometrial carcinoma: Mullany et al. have reported that downregulating HtrA1 expression in Hec1A and Hec1B cells (both of which are endometrial carcinoma cell lines) via RNA interference leads to a three- to four-fold increase in the invasiveness of these cells, whereas overexpressing HtrA1in Ark1 and Ark2 cells leads to a three- to four-fold decrease in their invasiveness [35].