TFF1 and retinoblastoma: Previous studies by our group revealed that only TFF3, but not TFF1 and TFF2 are expressed in the healthy human retina [11; 12], whereby retinoblastoma (RB) cell lines, established from malignant eye tumors of children, exhibit high levels of TFF1 [11; 12], but only trace amounts of TFF3 and no detectable TFF2. Most recently, we demonstrated that the expression of TFF3 in retinoblastoma cell lines is regulated epigenetically [12].