ACSL4 and viral infectious disease: Moreover, shrunken mitochondria, a morphological hallmark of ferroptosis (6), were observed in ACSL4+/+ cells upon CV-A6 infection (Fig. S4C, image 3, red arrow) but not in mock-infected cells (Fig. S4C, images 1 and 2) or in ACSL4−/− cells with virus infection (Fig. S4C, image 4).