Type IV collagen stimulates β1 integrin dependent migration of SCC25 cells. SCC25 cells were plated on plastic (pl) tissue culture dishes or type IV collagen (col) coated plates. Some cultures were preincubated with antibodies which block attachment by β1 or β4 integrin subunits. The number of cells which migrated into the blank area of the plate within 24 hours was counted. These experiments were performed three times with similar results. Error bars indicate SEM.