Skip to main content

Table 1 Polyploidy and expression of p57 and p21 in mice

From: Cip/Kip cyclin-dependent protein kinase inhibitors and the road to polyploidy

Tissue p57 p21 Polyploid Mechanism
Placenta[18] + + + Endoreduplication
trophoblast stem cell→giant cell     
Bone Marrow[4] - + + Endomitosis
megakaryoblast→megakaryocyte     
Liver[3] + + + Acytokinetic Mitosis
hepatocyte development     
Skeletal Muscle[13] + + + Cell Fusion
myoblast→myotube     
Bone[15] ? + + Cell Fusion
monocytes→osteoclasts     
Placenta[8, 14] ? + + Cell Fusion
Syncytiotrophoblasts     
Heart Muscle[5, 6, 19] + + +* ?
cardiomyocytes→myotube     
Skin[9] + + +* ?
basal epithelial cell→keratinocyte     
Kidney[10] + - +* ?
primitive podocyte→mature podo     
Eye[7, 11] + ? ?  
lens epithelial cell→fiber cell     
Bone[12] + + ?  
osteoblast→bone     
Cartilage[16, 17] + ? ?  
Chondrocytes→fiber cell     
  1. → Indicates expression of p57 and p21 up-regulated during normal cell differentiation.
  2. * Polyploidy results from injury (e.g. heart attack) or infection.