We first studied the effects of EPO and romiplostim onthe growth of LA-7 cells using the MTT assay to evaluate the safetyof using EPO and romiplostim in vivo because LA-7cells express EPO receptors.33 The cellviability remains constant after 24 or 48 h exposure to differentconcentrations of rHuEPO (0.01–100 IU/mL) and romiplostim (0.01–100ng/mL), which indicated that rHuEPO and romiplostim exhibit no stimulatoryeffects on the growth of LA-7 breast cancer cells in vitro (Figure S1A,B). Here, EPO is linked to breast cancer.