Details of chromosome localization of predicted C. elegans RTK genes described in this paper. Symbols are as follows (black arrows) RTK genes; (black arrowheads) RTK pseudogenes; (gray arrows) chitinase genes; (gray arrowheads) other genes. (A) clustering of genes encoding known and putative RTKs with a short extracellular region and chitinase-like genes on chromosome II. (B) Predicted RTK genes on chromosome III. (C) Predicted RTK and chitinase-like genes on chromosome V. (D) Predicted and known RTK genes on chromosome X.