To investigate the effects of cardiac glycosides in human neurons, we utilized two additional iPSC-derived neural progenitor cell (NPC) lines: MGH-2046-RC1 derived from an individual with frontotemporal dementia (FTD) carrying the autosomal dominant mutation Tau P301L (P301L), and MGH-2069-RC1 derived from a healthy individual directly related to MGH-2046 (WT). Here, MAPT is linked to frontotemporal dementia.