However, studies by Lloyd and Yin found no evidence for the low molecular weight products reported by other groups using an OVCAR-3 cell line [28,40]. Later they reported a precursor form of CA125 of approximately 400 kDa in an OVCAR-3 cell line, from which the mature form of the protein becomes assembled [28]. It is noted that only the mature protein form is released into the surrounding medium [28]. Additionally, the low molecular weight forms reported by other groups were assessed as possible degradation products by using trypsin [28]. This resulted in no defined, prominent molecular weight bands on a SDS-PAGE gel [28]. Furthermore, our research has not found evidence of low molecular weight forms of CA125 in human ascites [41]. Here, cross-reactivity of the employed M11-like and OC125-like antibodies was shown by two-dimensional western-blotting, mass spectrometric identification and spiking experiments. Therefore, the existence of lower molecular weight forms of CA125 remains uncertain.