Fig. 5. BRII and BRIa-ca are both necessary for the activation of the Smad pathway. A431 cells were transfected with various combinations of BRIa, BRII, BRIa-ca and BRII-KR, and the pSBE-Luc. For normalisation, the renilla luciferase construct pRLSV40 was co-transfected and the emission measured. Only co-transfection of BRIa-ca with BRII or co-transfection of BRIa and BRII with addition of BMP-2 leads to activation of the reporter. The data indicate that BRII is necessary for the activation of the Smad pathway.