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 T325-p
ERK1 T331-p , S374-p
ERK2 T325-p
ERK2 T331-p , S374-p
p90RSK S362-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 S374-p
ERK2 T325-p , T331-p
EGF T325-p , T331-p , S362-p
LPA T325-p
MG132 S362-p , S374-p
NGF T325-p , T331-p , S362-p , S374-p
PDGF T325-p
serum S362-p , S374-p
tamoxifen S362-p
U0126 T325-p , S362-p , S374-p