Inhibition of HSP90AB1 was effective in a canine OSA cell line [82] suggesting that an HSP90 inhibitor may be effective for tumors with amplification and overexpression of HSP90AB1. STA‐1474, an HSP90 inhibitor, has exhibited efficacy in dogs with mast cell tumors, an anti-tumor response in canine OSA cell lines and showed a partial response in 1/10 dogs and stable disease in 2/10 dogs with metastatic osteosarcoma [82–84]. The gene discussed is HSP90AB1; the disease is mast cell neoplasm.