Figure 4

PHI inhibits IL-6 receptor expression and reactivates p21 expression in RPMI8226 myeloma cells. The RPMI8226 myeloma cells were cultured with 5 μM of PHI for 24 and 48 hours, respectively. The proteins were extracted from the cell lysates. The expression level of IL-6 receptor subunits, gp80 and gp130, as well as p21 protein were determined by Western blot analysis as described in Material and Methods. β-actin level in the same blot was used as an internal loading control for protein amount.