Where to find drug-gene interactions with IC50 values?

Question

[entheologist33]

I have a database of genes and a database of substances. I need to find a way to procure gene to substance interactions with their binding constants. BindingDB looks good but their API has been down every time I checked. There must be some central database of IC50/binding constants of ligands and proteins. Does anyone know of a database like this?

[Ron]

Maybe try this http://www.cancerrxgene.org and http://www.maayanlab.net/LINCS/DCB/ They have drug sensitivity values in cell lines.