Your Query returns 2 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
activin-bNC_0043537227dACT    CG11062    activin    dActivin    activin-beta   
activin-bNM_1436857227dACT    CG11062    activin    dActivin    activin-beta   

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* OMIM link based on symbol match for human and mouse.

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Text2Knowledge ... Yong Huang 2002