Tumor suppressor that inhibits cell proliferation and promotes apoptosis. Modulates the activity of protein arginine N-methyltransferases, including PRMT3 and PRMT5 (By similarity). Interacts (via FERM domain) with CADM1. Interacts (via FERM domain) with PRMT3; the interaction is direct and inhibits the protein-arginine N-methyltransferase activity of PRMT3. Interacts with PRMT5. Interacts with PRMT6. Has the complete spectrin--actin-binding (SAB) domain and fully interacts with spectrin and actin. Detected in the cytoplasm of actively dividing cells. Experimental confirmation may be lacking for some isoforms. Detected in brain (at protein level). Highest expression in brain, lower in testis, adrenal gland, heart and kidney. Also present in muscle and epithelial cells. Isoform 1 is expressed in brain, isoform 2 is expressed in heart and isoform 3 is mostly expressed in kidney but also in heart and brain. Isoform 6 seems to be most abundant in kidney while isoform 4 and isoform 5 are predominantly expressed in heart and brain. The complete SAB domain is present only in the heart-specific isoforms (isoform 2 and isoform 5). Inferred from the cDNA sequence of Ref.2. Truncated N-terminus.