SPI1 and mantle cell lymphoma: Additionally, the downregulation of CD52 and CD37, and reduced activity of the transcription factor SPI1/PU.1 were determined over a 240-day treatment period by Rendeiro et al., whereas we detected an upregulation of CD52, CD37, and increased activity of SPI1/PU.1 in our MCL cell line model after 48 h ibrutinib treatment [32].