BTK and neoplasm: Western blot analyses revealed a decrease in both BTK- and ERK-phosphorylation in tumor burdened spleens from both Eμ-TCL1 and Eμ-TCL1;p53R172H/+ mice (Figures 3c and d), illustrating the robust downstream inhibitory effect that ibrutinib has on the BCR signaling pathway regardless of p53 status.