NANOG and hydrops fetalis: Cell cycle assays also showed that the ectopic expression of NANOG or the overexpression of PBX1 also significantly increased the proportion of HF-MSCs in the S phase to 14.56 ± 2.43% in the NANOG group and 11.79 ± 1.84% in the PBX1 group in comparison to that of the vector group (7.87 ± 1.72%).