This effect of forced TFF3 expression could be verified and generalized in (i) the equally well-established RB cell lines WERI-Rb1 [6], derived from an unilateral RB tumor, (ii) RBL-13 cells, likewise derived from an unilateral RB tumor, but exhibiting different growth kinetics and tumor formation capacities [21; 24] and (iii) RBL-15 cells derived from a bilateral RB tumor [21] (Fig 2A). The gene discussed is TFF3; the disease is retinoblastoma.