In addition, when comparing the effect of HF and DWN12088 on the levels of general proteins, the levels of proline‐rare proteins such as cyclin D1 were decreased more sensitively in mutant‐expressing cells as the concentrations of DWN12088 were increased, whereas the sensitivity to HF was similar between control and mutant‐expressing cells (Fig 6K). Here, CCND1 is linked to hydrops fetalis.