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Fig. S6. Retinoic acid signaling is required for Xenopus lung bud growth but not specification. (A,B) Embryos were cultured in 10 µM BMS493, a pan retinoic acid receptor inhibitor, from stages 25 to 35 (A) or stage 25-42 (B), and assayed by in situ hybridization with the indicated probes. (A) Although inhibition of RA signaling did not prevent pulmonary specification (Fig. 3), expression of dkk1 was upregulated as expected based on the finding that Dkk1 is upregulated in Raldh2-/- mutant mouse embryos (Chen et al., 2010). (B) A dorsal view of isolated gut tubes shows that inhibition of RA signaling from stages 25-42 inhibited the growth of sftpc-expressing lung buds. |