CXCR4 and neoplasm: Given that CXCR4 signaling is known to regulate anoikis in tumor progression [44, 45], 66cl4-luc GRK3-deficient cells were compared to 66cl4-luc control cells for their apoptotic response to detachment; data showed that there was no intrinsic difference in anoikis between the different 66cl4-luc tumor types in vitro (Fig 6C).