Table 1

Polyploidy and expression of p57 and p21 in mice
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



→ Indicates expression of p57 and p21 up-regulated during normal cell differentiation.

* Polyploidy results from injury (e.g. heart attack) or infection.

Ullah et al. Cell Division 2009 4:10   doi:10.1186/1747-1028-4-10

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