(A) Mutant-type TPO manifested the same level ofTPO mRNA as wild-type. L929 cells were transfected with 10 μg of pActC, pAct-wTPO, or pAct-mTPO, respectively. By Northern blot analysis, TPO mRNA level in the transfected cells showed no definite difference between pAct-wTPO and pAct-mTPO. (B) TPO production definitely differed between pAct-wTPO and pAct-mTPO. TPO concentration in the conditioned media was analyzed by ELISA. TPO released by pAct-wTPO transfected L929 cells was arbitrarily assigned to a value of 1.0, and the results are shown as the mean ± SD. The analysis was performed in duplicate assays and the results were reproducible.