In order to assess whether INPP4B overexpressing ER+ breast cancer cells are sensitive to pyrvinium in 3D culture models, MCF-7 or T47D cells expressing GFP-vector or GFP-INPP4B were cultured in Matrigel for 4 days to form 3D spheroids, then treated with pyrvinium and/or 4-OHT for 72 h (Figure 5). Here, ESR1 is linked to breast cancer.