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
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