Two interpretations are possible: a) in MM cells, the response to E2 is ER-dependent and some cells such as Karpas 620, OPM-2 or ARH-77 do not express functional ER and/or associated transcription cofactors; b) the response to E2 is ER-independent and E2-resistant cells lack signalization molecules engaged in the survival, proliferation or apoptosis pathways necessary for growth inhibition. Here, ESR1 is linked to Miyoshi myopathy.