Table 2.

The effects of the DM and five of the analogs on various in vitro kinase assays

	IC50 (nM)
	ALK2 (BMPR-I)	ALK5 (TGFβR-I)	AMPK	KDR (VEGFR2)	PDGFRβ
DMH1	107.9	No	No	No	No
DMH2	42.8	1578.0	3527.0	2418.0	n.t.
DMH3	26.7	998.0	1940.0	2062.0	n.t.
DMH4	3558.0	No	8038.0	161.0	n.t.
DM	148.1	10,760.0	234.6	25.1	n.t.
LDN-193189	40.7	565.0	1122.0	214.7	n.t.
Staurosporine	4531.0	10,640.0	<1.0	3.29	6.14

Shown are the IC50’s (concentrations causing 50% inhibition) of DM and the analogs for the in vitro kinase assays using the following purified human enzymes: the BMP type-I receptor activin receptor-like kinase 2 (ALK2/BMPR-I), the TGFβ type-I receptor activin receptor-like kinase 5 (ALK5/TGFβR-I), the VEGF type-2 receptor (VEGFR2/KDR), the AMP-activated protein kinase (AMPK) and the platelet-derived growth factor receptor-β (PDGFRβ). In in vitro kinase assays, DM was relatively nonspecific, targeting ALK2, AMPK and KDR with IC50s less than 250 nM. LDN-193189 was slightly more selective, but it still had significant effects against ALK5 and KDR. By comparison, DMH1, DMH2 and DMH3 were much more selective ALK2 inhibitors. In particular, DMH1 had no detectible activity against any of the kinases tested besides ALK2. DMH4 was a selective KDR inhibitor with modest effect on ALK2 (IC50 3.6 μM) and minimal effect on AMPK (IC50 8.0 μM). Nonspecific kinase inhibitor staurosporine was used as a control. All of the reactions were carried out in the presence of 10 μM ATP. “No,” no inhibition; “n.t.,” not tested.