Pdgfb is a Notch-independent target of β-catenin signaling in ECs. (A) HUVECs co-cultivated with control^−D, Wnt1^−D, and Dkk1^−D GL261 cells. qRT-PCR (n = 4) for human PDGFB regulated by Wnt1^−D or Dkk1^−D (ns) compared with control^−D (gray line; *, P < 0.05). (B) qRT-PCR for Pdgfb gene regulated in MBEs stimulated by Wnt3aCM for 18 and 48 h compared with controlCM (gray line; n = 4; *, P < 0.05; ***, P < 0.001). (C, left) qRT-PCR for Axin2 and Pdgfb regulated in β-catenin–deficient ECs transduced with LefΔN-βCTA compared with the vector control (gray line; n = 4; *, P < 0.05; **, P < 0.01). (right) Representative Western blot (n = 1) for PDGF-B from LefΔN-βCTA ECs compared with the vector control; top band shows the nonreduced (PDGF-BB) and bottom band reduced protein (PDGF-B). Densitometric analysis shows the summarized values for both forms of PDGF-B of samples loaded twice. (D) qRT-PCR of β-catenin–deficient ECs (control) or transduced with LefΔN-βCTA grown for 24 h either on gelatin- or Dll4-coated dishes (n = 3). Notch pathway induction was monitored by Hes1 expression (*, P < 0.05; **, P < 0.01). Notch signaling was blocked by Dll4-Fc. Error bars indicate SEM.