Table 3.

The basic activity of the cell cycle regulators and other factors associated with melanocytes senescence

The cell cycle regulator	The level of expression/activity during senescence
Cyclin E	↓ Protein level
p16INK4a	↑ Expression
Protein RB1	Dephosphorylation
CDK2 and CDK4	↓ Activities
Transcription factor E2F4	↑ Association with RB1
p300/CBP histone	↓ Activity
acetyltransferases
Extracellular matrix proteins	↑ Protein level
MAPK-signaling pathway	Inactivation
p53	Melanocytes senescence is independent of p53, probably except for situation with deficient p16/RB1 pathway