Answer
Cells with only the extracellular part of integrin could still bind to the extracellular matrix, but they could not also attach internally to the cytoskeleton. This would end cell movement and processes in development which rely on cell movements, such as gastrulation and neurulation.
Work Step by Step
Loss of the interior part of integrin removes much of the function of the protein. This resembles, largely, the loss of the whole protein, except for binding to the extracellular matrix.
