SLC4A1 and osteosarcoma: AE1,3 is an antibody mixture reactive against cytokeratins 56.5, 50, 51, 48, 40, 67, 66, 65, 64, 59, 58, 56 and 52 KD as described by Moll et al.10 These epithelial osteosarcomas contain a component of cells with eccentrically located vesicular nuclei, prominent nucleoli and abundant pale eosinophilic cytoplasm.6 Such osteosarcomas require distinction from metastases to bone.