Let \( A = I_{2} - 2MM^{T} \) where \( M \) is a real matrix of order \( 2 \times 1 \) such that the relation \( M^{T}M = I_{1} \) holds. If \( \lambda \) is a real number such that the relation \( AX = \lambda X \) holds for some non-zero real matrix \( X \) of order \( 2 \times 1 \), then the sum of squares of all possible values of \( \lambda \) is equal to ________.