This entry represents a group of ankyrin repeat-containing proteins, including ABTB1 from humans, Btb3 from fission yeasts, YIL001W from budding yeasts and At2g04740 from Arabidopsis. ABTB1 is an anti-proliferative factor that may act as a mediator of the phosphatase and tensin homologue (PTEN) growth-suppressive signaling pathway [].