Antibody:	Anti-Phospho-Smad1/5/8
Detection system:	Secondary antibody coupled to Cy5
Assay notes:	The specificity of the antibody used was not detailed; all family members have been annotated. The antibody used recognizes the phosphorylated form of the protein.

Structure	Level	Pattern	Image	Note
TS17: neural tube lateral wall	Present	Regionally restricted	1K , 1J	Expressed in the most dorsal progenitor cells immediately adjacent to the roof plate.

Structure	Level	Pattern	Image	Note
TS19: neural tube lateral wall	Present	Graded	1M , 1L	Expanded in the ventricular zone of the dorsal-most spinal cord, with the highest levels of activation seen in the cells flanking the roof plate. Expressed in both post-crossing axons and Cntn2+ commissural axons.

Structure	Level	Pattern	Image	Note
TS17: neural tube lateral wall	Present	Regionally restricted	S2A	Expressed in the most dorsal progenitor cells immediately adjacent to the roof plate.

Structure	Level	Pattern	Image	Note
TS17: neural tube lateral wall	Present	Regionally restricted	S2B	Expressed in the most dorsal progenitor cells immediately adjacent to the roof plate, similar as in the control.

Structure	Level	Pattern	Image	Note
TS19: future spinal cord	Present	Regionally restricted	S2C	Expressed in the commissural axons before and after crossing the floor plate.

Structure	Level	Pattern	Image	Note
TS19: future spinal cord	Present	Regionally restricted	S2D	Substantial decrease (40%) in expression in the commissural axons before and after crossing the floor plate compared with the control.

Structure	Level	Pattern	Image	Note
TS17: neural tube lateral wall	Present	Regionally restricted	S2E	Expressed in the most dorsal progenitor cells immediately adjacent to the roof plate.

Structure	Level	Pattern	Image	Note
TS17: neural tube lateral wall	Present	Regionally restricted	S2F	Decreased expression (20%) in the most dorsal progenitor cells immediately adjacent to the roof plate, compared with the control.