The basal level of Btk expression was not associated with different sensitivity to ibrutinib in GCB-DLBCL cell lines. (A) Total RNA from untreated Jurkat, OCI-Ly3, SU-DHL-16, LY7 and normal B cells were extracted by TRIzol reagent and performed a reverse transcription. RealTime-PCR analysis was done to determine the quantities of Btk mRNA. β-actin was used as the internal control gene for normalization. Results were expressed as the mean ± SD of three independent experiments. The differences in groups were assessed by Student’s t-test (p < 0.05). (B) Untreated Jurkat, OCI-Ly3, SU-DHL-16, LY7 and normal B cells were lysed using RIPA buffer for total protein. Western Blot was performed to detect the expression of p-Btk and Btk protein. β-actin was included as a loading control. Results were shown from one of three experiments and the representative results were shown in the figures.