HAS1 and ovarian cancer: We started to determine the mechanism of hyaluronan accumulation in ovarian cancer by analyzing the expression profiles of hyaluronan synthases and hyaluronidases in a clinically defined set of tumors, and found that a significantly decreased HYAL1 expression correlates with lower hyaluronidase activity and elevated hyaluronan content of the tumors, while HAS expression was not as consistently associated to the accumulation of hyaluronan.