GDF15 and prostate cancer: However, a number of transformed cell lines, including the choriocarcinoma cell line BeWo, the monocytoid cell line from which GDF15 was initially cloned, U937, and the prostate cancer cell lines, PC-3 and LNCaP, all secrete an unprocessed proGDF15 dimer where the propeptide domain has not been proteolytically cleaved (29).