BCR-ABL is a constitutively activated tyrosine kinase that is associated with chronic myeloid leukemia. RANK is constitutively expressed in mammary epithelial tissues. Macrophages that constitutively express MARCO are within the spleen marginal zone and medullary lymph nodes. It is ubiquitously and constitutively expressed in healthy tissues. Bcr-Abl codes for a tyrosine kinase, which is constitutively active, leading to uncontrolled cell proliferation. CD28 is the only B7 receptor constitutively expressed on naive T cells. However, if either kinase is constitutively active, neurons survive even without NGF. The "lacZYA" repressor is constitutively expressed. GSK3s are constitutively active enzymes implicated in several important regulatory processes. GudB is constitutively transcribed whereas RocG is tightly regulated. These mutations allow the pathway to be constitutively activated, regardless of the presence of mitogens. In cancer, "c-myc" is often constitutively (persistently) expressed. Mutating Ser-253 to Ala-253 makes FOXO1 constitutively active. STAT3 can promote oncogenesis by being constitutively active through various pathways as mentioned elsewhere. This form of TAZ always resides in the nucleus and therefore is constitutively active.