Antibody:	Anti-pERK
Assay notes:	The antibody used recognizes the phosphorylated form of the protein. The specificity of the antibody used was not detailed; both family members have been annotated.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	3B , 3A	Expressed from the posterior to the prospective somite S-2 region during phase II.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	3D , 3C	Expressed from the posterior to the prospective somite S-2 region during phase III.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	3F , 3E	During phase I, when S-2 became S-1 after segmentation, pMapk1/3 expression was down-regulated and the whole Notch1 domain in S-1 was freed from pMapk1/3.