Zac1 regulates TGFβII signaling in the retina. (a-f) Co-expression of TGFβRI (green (a-c)) and TGFβRII (green (d-f)) with Ccnd1 (red, proliferating progenitors (b,e)) and Pax6 (red, amacrine cells (c,f)) in E18.5 > 4DIV wild-type retinal explants. (g-l) TGFβII expression in E18.5→4DIV wild-type (green (g-i)) and Zac1+m/- (green (j-l)) retinal explants co-labeled with Pax6 (red, amacrine cells (i,l)). Arrowheads mark double+ cells. Asterisk in (j) marks reduction in onbl/INL expression. (m,n) Expression of pSmad2/3 in E18.5→4DIV wild-type (m) and Zac1+m/- (n) retinal explants. (o) Western blot analysis of TGFβII, pSmad2/3, total Smad2/3, and β-actin. Asterisks in (o) indicate mutants with reduced expression of TGFβII or pSmad2/3. (p,q) Quantitation of expression levels normalized to β-actin via densitometry for TGFβII (p) and pSmad2/3 (q).