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.

ERK1 S21-p
ERK2 S21-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.

ERK1 S21-p
ERK2 S21-p
Regulatory protein:
C/EBP-alpha K161-sm
CD34 S21-p
FUT4 S21-p
TfR S21-p
AG1296 S21-p
butyrate S21-p
FL S21-p
G-CSF K298-ac , K302-ac
hemin S21-p
imatinib S21-p
insulin S21-p
IRC-084864 S21-p
MG132 K161-ub
MLN-518 S21-p
PD98059 S21-p
PDGF S21-p
phorbol_ester S21-p
serum S21-p
siRNA K161-sm
U0126 S21-p
vorinostat K161-ac