Moreover, since β-arr-biased signaling requires phosphorylation of GPCRs by GRKs to promote high-affinity binding of β-arr to GPCRs and GRK subtypes might have preferential phosphorylation and trigger unique conformational changes in GPCRs, studies of β-arr-biased signaling might consider also the involvement of GRKs in cancer-related signaling pathways (Heitzler et al., 2012). This evidence concerns the gene GZMK and cancer.