On 2018 Jan 08, Massimiliano Tognolini commented:

Compound 1 (2,5-dimethylpyrrolyl benzoic acid) has been used as an Eph/ephrin inhibitor to assess the role of Eph/ephrin system virus entry. Unfortunately, compound 1 is PAINS (Pan Assay INterference substance) giving positive results in a large number of biological assays (Baell JB, 2010). The compound is highly reactive and spontaneously forms a mixture of non-specifically reactive polymers (Zhu W, 2013). Discoverer of Compound 1 themselves retracted their observation by publishing: "...the newly synthesized compound 1 did not show detectable inhibition of ephrin-A5 binding to EphA4-Fc in ELISAs or EphA2 phosphorylation in cells stimulated with ephrin-A1 Fc. ...when left exposed to air at room temperature in dry form, compound 1 acquired a progressively darker brown color. Concomitantly, the compound became progressively more active in ELISAs measuring inhibition of ephrin-A5-EphA4 binding.” (Noberini R, 2011). Scientists were advised about the use of compound 1 by the writer and colleagues in 2014 (Tognolini M, ACS chem neuroscience and Lodola A, JVI). In conclusion compound 1 IS NOT a RELIABLE EPH/EPHRIN ANTAGONIST.

On 2018 Jan 08, Massimiliano Tognolini commented:

Compound 1 (2,5-dimethylpyrrolyl benzoic acid) has been used as an Eph/ephrin inhibitor to assess the role of Eph/ephrin system virus entry. Unfortunately, compound 1 is PAINS (Pan Assay INterference substance) giving positive results in a large number of biological assays (Baell JB, 2010). The compound is highly reactive and spontaneously forms a mixture of non-specifically reactive polymers (Zhu W, 2013). Discoverer of Compound 1 themselves retracted their observation by publishing: "...the newly synthesized compound 1 did not show detectable inhibition of ephrin-A5 binding to EphA4-Fc in ELISAs or EphA2 phosphorylation in cells stimulated with ephrin-A1 Fc. ...when left exposed to air at room temperature in dry form, compound 1 acquired a progressively darker brown color. Concomitantly, the compound became progressively more active in ELISAs measuring inhibition of ephrin-A5-EphA4 binding.” (Noberini R, 2011). Scientists were advised about the use of compound 1 by the writer and colleagues in 2014 (Tognolini M, ACS chem neuroscience and Lodola A, JVI). In conclusion compound 1 IS NOT a RELIABLE EPH/EPHRIN ANTAGONIST.