IFNγ triggers the p21 upregulation and TDP-43 proteinopathy in iPSC-derived motor neurons. A, qRT-PCR analysis for each experimental group quantifying the time-dependent expression of p21, the early transcriptional target of p53 signaling. UT, untreated control group; IFNγ, 5 ng/ml IFNγ-treated group. Flow of hypothesis for this study (right panel). B, Immunocytochemistry assay of WT and Q331K^+/− mutant cultures at Days 25, 32, and 40, showing a significant cytoplasmic translocation and aggregation of the TDP-43 protein in response to the IFNγ stimulation at the later phases of both cultures. C, Quantitative analysis of the cytoplasmic TDP-43 translocation for each experimental condition (error bars indicate SD, n = 5 biological replicates; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001; ns, not significant).