Effects of all-trans Retinoic Acid (RA) on the adhesion and motility of metastatic human lung cancer cell subline (PGCL3) were observed in vitro. The results showed that treatment of PGCL3 with RA for 5 days decreased the adhesion of cells to laminin substrate and the migrative ability through the polycarbonate filter of Boyden chamber, and those inhibitory effects became more obvious with the increase of RA concentration. Further investigation by DNA-RNA dot blot hybridization and immunohistochemistry denoted that RA-treated PGCL3 cells expressed lower level of 67-KD LN-R compared to untreated cells. The data from DNA-RNA dot blot hybridization also showed that RA could reduce the expression of AMF-R significantly. These results raise the possibility that the previously reported suppression by RA of PGCL3 invasion and metastasis may be related to suppression of cell adhesion and motility resulting from the decreased expression of the LN-R and AMF-R respectively.