IL4 and Alzheimer disease: The experiment was set up with three groups, each with six biological replicates (n = 6): the control group (K) was normal cultured HaCaT cells; the model group (M) was AD model cells established by TNF-α and IL-4 stimulation; and the treatment group (Y) was AD model cells treated with methotrexate (50 μM, for 24 h).