Fig. 5. xTsg^W67G inactivates an isolated CR module but not Noggin or a dominant-negative BMP receptor. (A) RT-PCR analysis of animal caps injected with the indicated mRNAs. Xenopus CR1 mRNA (80 pg total) was injected alone or together with 1 ng xTsg or xTsg^W67G mRNA. (B) Microinjection of 20 pg CR1 mRNA induces secondary axes at high frequency (79%, n=79). (C) Formation of secondary axes was completely blocked by co-injection of 250 pg xTsg^W67G mRNA (0%, n=39). (D) Secondary axes were efficiently induced by microinjection of 1 ng mRNA encoding a dominant-negative BMP receptor (tBR; 67%, n=49). (E) Axis-inducing activity of tBR was not affected by co-injection of 250 pg xTsg^W67G (65%, n=57). (F) Injection of 0.1 pg Noggin mRNA induced secondary axes (68%, n=40). (G) The activity of Noggin was not inhibited by co-injection of 250 pg xTsg^W67G mRNA (67%, n=42).