Your Query returns 2 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
p21Cip1NM_00766910090P21    CDKI    CIP1    SDI1    Waf1    mda6    CAP20    Cdkn1    p21WAF    Cdkn1a   
p21Cip1BC00204310090P21    CIP1    SDI1    Waf1    mda6    CAP20    p21WAF    CDKI    Cdkn1a   

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

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Text2Knowledge ... Yong Huang 2002