CXCL12 and ovarian carcinoma: While parental HeyA8 cells do not express CXCL12 as determined by QRT-PCR (data not shown), HeyA8-CXCL12-GL cells secrete approximately 12 ng/ml CXCL12 in a 24 hour period, which is comparable to values reported for other ovarian cancer cells that secrete this chemokine endogenously [19], [31].