(A) Immunoblots of protein lysates from Null- or TFEB/3 knockout-MEF cells incubated in the presence of DMSO (Control) or Tunicamycin (Tun.) (0.1 µg/ml) for the indicated times. Data are representative of three independent experiments.(B) Quantification of ATF4 protein levels in Null- or TFEB/3 knockout-MEF cells treated as indicated in (A) (mean ± SD of the ATF4 to actin protein ratio from three independent experiments, student's t-test versus the corresponding time point in Null-MEF cells, ns= not significant, **p < 0.01). 