BMP inhibition by LDN is associated with deactivation of p38MAPK. Phosphorylation states of reported downstream kinases responsive to SMAD-independent BMP signaling were probed in western blotting experiments and compared with total protein levels with β-actin as a loading control. (A) p38MAPK Thr/Tyr phosphorylation was markedly downregulated after overnight treatment with either full-dose LDN or LDN50 to achieve ∼100% or 50% BMP signaling inhibition, respectively, with co-depletion of SMAD1/5 by dox induction resulting in no significant changes in p38 phosphorylation. In contrast, (B) Thr/Tyr phosphorylation of ERK1/2, (C) Thr/Tyr phosphorylation of JNK, and (D) Ser phosphorylation of AKT displayed no significant changes compared with controls for any treatment. (E) These relationships are presented as quantified densitometry data, where **P < .01.