The findings of Adithi et al. on MMP-2 and MMP-9 expression in RB concur with other studies on the expression of these MMPs in RB.70 Examination of the LHßTag murine transgenic RB model showed that MMP-9 was strongly upregulated and MMP-2 was weakly upregulated.71 It is clear that in addition to MMP-2 and MMP-9, TIMP-2, TIMP-1, EMMPRIN also play important roles in RB invasion. This evidence concerns the gene MMP9 and retinoblastoma.