Sequence alignments of TSLP, CRLF2, and EPOR. (A) Lack of homology of mouse and human CRLF2 amino acid sequences. Extracellular domain (green), transmembrane region (pink), and intracellular domain (blue). Blue box represents box 1 necessary for JAK activation; red box, cytokine receptor motif WSXWS sequence. (*) denotes identity; (:) indicates strong homology; and (.) indicates weak homology. (B) Lack of homology of mouse and human TSLP amino acid sequences. (C) Comparison of human CRLF2 and EPOR to show limited homology within box 1 of both proteins.