Various isoforms of human CADM1 and CADM2. Exon organizations of human CADM1 (A) and CADM2 (B) are shown. Exons present in all isoforms are indicated by gray rectangles, and exons present in only some isoforms are indicated by red, blue, green, yellow, magenta, or black rectangles. The canonical isoform is designated CADM1 or CADM2, and the other isoforms are designated by appending numbers of exons not present in the canonical isoform (e.g., CADM1+ex8). One of the noncanonical CADM2 isoforms, CADM2+ex9(1), has the same exon 1 as the canonical CADM2, whereas another noncanonical isoform, CADM2+ex9(2), has a different exon 1. Schematic domain organizations of CADM1/2 are shown below the corresponding exons. Amino acids encoded by exon 8, exon 9, and exon 10 of CADM1 and exon 9 of CADM2 in the stalk regions are also shown. V, Ig-like V-type domain; C, Ig-like C2-type domain; TM, transmembrane domain.