VPA effects on Tax and HBZ expressions in CD4⁺ T cells from HAM/TSP patients. (A) Patients' CD4⁺ T cells were cultured for the indicated times with 1mM (■) or 5mM VPA (♦). The curves illustrate VPA induction of Tax expression compared with the corresponding nontreated sample (medians and first quartiles of 5 patients for each concentration). (B) Box plot of the HBZ-mRNA levels, expressed in arbitrary units (AU), in CD4⁺ T lymphocytes from HAM/TSP patients after 5 days of culture with or without the indicated VPA concentration (5 patients per concentration). Horizontal lines are the bold medians and, from bottom to top, 10th, 25th, 75th, and 90th percentiles.