Cells derived from CD44ex10 local tumors exhibit increased homotypic aggregation in vitro. Single-cell suspensions of the CD44ex10 local tumors and the less common vector-only, CD44H, CD44ex7-14, and CD44ex10-14 local tumors were prepared, plated, cultured, and monitored for changes in cellular morphology and aggregation in vitro. Cell suspensions from local tumors of representative independently derived CD44ex10 Namalwa transfectants (_{I or II}) or vector-only, CD44H, and CD44ex7-14 transfectants are shown. As indicated, cell suspensions from CD44ex10 local tumors exhibited dramatically increased homotypic aggregation.