Expression of integrin α_E(CD103)β₇ capacitates K562 cells to move in an amoeboid fashion on E-cadherin. (A) K562 cells were double-transfected with the murine β₇ integrin subunit and either wild-type α_E(CD103) or α_E(CD103) locked in a constitutively active (α_E-open) or inactive (α_E-closed) conformation. Control cells were transfected with the empty vector (pcDNA). Transfectant cells were seeded on recombinant murine E-cadherin and images were taken every 2.5 minutes. Shape changes of a representative cell for each condition are shown. indicates examples of filopodia and/or cell protrusions. This panel corresponds to Videos S1,S2. Scale bar = 10 μm. (B) K562 cells were transfected with integrin α_E-WT/β₇, integrin α_E-open/β₇, integrin α_E-closed/β₇, or the empty vector (pcDNA) as detailed in “Cell culture and transfections.” The transfectants were monitored for 60 minutes on immobilized E-cadherin (), on uncoated plastic surfaces (), or on collagen (▨). In addition, transfectants plated on E-cadherin were treated with a function-blocking antibody directed against α_E(CD103) () or were cultured in the presence of cytochalasin D (□). The number of cells moving in an amoeboid fashion and producing protrusions/filopodia is depicted relative to the control (wild-type α_E(CD103)β₇-transfected cells adhering to fetal calf serum–coated plastic surfaces). Values shown represent the means (± SEM).