CDK4 and hydrops fetalis: Additionally, the results of cell cycle analysis revealed that HF induced an increase in the percentage of cells in G0/G1 phase (Figure 1E), with down‐regulation of cyclin D1, cyclin‐dependent kinase 4 (CDK4), and cyclin‐dependent kinase 6 (CDK6) and up‐regulation of total p53 along with p‐p53 ser15 and p21Cip1 (Figure 1F).