The GFP-ML1Nx2 probe labels punctate structures even in the absence of PIKfyve.

Images show a representative wild-type and PIKfyve knock-out (KO) ES cells expressing the GFP-ML1Nx2 probe. Note the fluorescent puncta in the PIKfyve KO cell which showed swollen endosomes, a hallmark of PtdIns(3,5)P2 deficiency. Data are representative of 11 cells, scale bar = 15 μm.