Fig. 8. The activation of Erk MAP kinases in the ureteric bud is not detectably affected when kidneys are incubated in the presence of 10 ng/ml BMP2. (A) The top panel shows a western blot of ureteric buds, isolated after an 8 hour incubation of complete kidneys with and without BMP2, probed with an antibody specific for phosphorylated Erk1/2 (Erk-P). The bottom panel shows the same samples probed with an antibody that recognises both phosphorylated and non-phosphorylated Erk. (B,C) Micrographs of kidneys cultured in normal medium (C) and 10 ng/ml BMP2 (C) for 30 hours confirm that BMP2 inhibits ureteric bud morphogenesis.