Kinase, in vitro: 

An enzyme-substrate reaction that occurs in non-living experimental conditions such as a test tube. For example, a purified enzyme is reacted with a substrate protein or mixture of proteins or peptides.

CDK4 S246-p
CDK6 S246-p
 Putative in vivo kinases: 

An enzyme-substrate reaction that occurs within living cells; includes cultured cells, ex vivo samples, and intact organisms. In the case of kinases, the large number of protein kinases in intact cells makes exact identification of the responsible kinase challenging.

CDK4 S246-p
CDK6 S246-p
Phosphatases, in vitro:
PPP2CA S321-p
Putative upstream phosphatases:
PPP2CA S321-p
Regulatory protein:
mucolipin 1 S321-p
PPP1CA S321-p
PPP1CB S321-p
PPP3CA S321-p
PPP3CB S321-p
PRP4 S556-p
ceramide S321-p
EBSS S321-p
EGF S554-p , S556-p , S560-p
fingolimod S321-p
FK506 S321-p
ischemia S334-p , S548-p
LY2835219 S246-p
melatonin S321-p
NaAsO2 S321-p
NAC S321-p
nocodazole S548-p , S556-p , S560-p
okadaic_acid S321-p
SB202190 S554-p , S556-p , S560-p
siRNA S246-p , S321-p
Torin1 S246-p , S321-p
tunicamycin S321-p