We attempted a variety of culturing methods, such as fractional PB-CTC culture, growing CTCs in neurosphere and hypoxic conditions,9 or changing the media recipe after short culturing periods.18 None of the efforts proved effective, despite our experience with growing glioma stem cells.30,31 Ultimately, we successfully propagated CSF-CTCs using HMC-conditioned medium and supplemented with FGF and EGF. This evidence concerns the gene CSF2 and central nervous system cancer.