Abstract: Solutions to the problem of the invention are a method for selectively killing or removing a senescent cell, substance identification, and a method for purifying a senescent cell. Specifically, the invention includes an agent for removing a senescent cell, which is a drug for removing an in vivo senescent cell, the agent containing an inhibitor for glutaminase as an active ingredient, and a pharmaceutical composition containing the agent. The invention further includes a method for preparing a senescent cell, including the following steps (a) to (c): (a) synchronizing a cell with the G2 phase; (b) activating an intracellular p53 protein in the cell synchronized with the G2 phase; and (c) inhibiting polo-like kinase 1 (PLK1) activity in the cell treated in the step (b).

Abstract: The present invention is intended to provide a method for determining the prognosis of a hormone receptor-positive cancer (for example, an ER?-positive breast cancer, an ER?-positive endometrial cancer, etc.) or a method for assisting the determination of the prognosis, and a method for evaluating the sensitivity of the cancer to antihormone therapy or a method for assisting the evaluation of the sensitivity of the cancer to antihormone therapy. Specifically, the present invention relates to a method for determining the prognosis of a hormone receptor-positive cancer, or a method for assisting the determination of the prognosis, which comprises the following steps (a) and (b): (a) a step of detecting Fbxo22-positive cancer cells in a sample derived from the cancer tissues; and (b) a step of calculating the percentage of the Fbxo22-positive cancer cells to the cells present in the sample.