Table S1.

Primary antibodies used for immunohistochemistry

Antigen	Manufacturer and catalog no.	Concentration	Postfix	Protocol
ASCL1/MASH1	BD Pharmingen 556604	1:1,000	None	A
Cleaved caspase 3	Cell Signaling 9664	1:500	None	C
INSM1	Birchmeier laboratory guinea pig serum	1:20,000	None	A
KDM1A/LSD1	Abcam ab17721	1:200	None	A
MAP2	Millipore MAB3418	1:500	Overnight	A
MKI67/Ki67	Abcam ab16667	1:100	Overnight	C
NKX2-1	Santa Cruz Biotechnology sc-13040	1:500	None	B
OLIG2	Chemicon AB9610	1:500	Either	C
RCOR1	Neuromab clone K72/8	1:200	None	C
RCOR2	Rosenfeld laboratory rabbit serum	1:10,000	None	A

Slides were prepared for blocking in one of three ways. In protocol A, sections were incubated with PBS containing 0.1% TritonX-100 (PBS-Triton) for 30 min. In protocol B, slides were incubated in –20 °C acetone for 10 min, dipped in deionized water, and incubated in PBS for 5 min. Protocol C consisted of protocol B followed by treatment with 10 mM sodium citrate tribasic dihydrate containing 0.1% Tween-20, pH 6.0, for 40 min in an Aroma kitchen steamer.