RB1 and retinoblastoma: Rearrangements in HMGA2 gene leading to chimeric transcripts have been known to contribute to neoplastic transformation in mesenchymal tumors (Fusco & Fedele, 2007; Schoenmakers et al., 1995), but genetic alterations are not the cause of HMGA2 induction in RB and RB1 inactivation does not seem to be a direct driver for HMGA2 expression as not all RB tumors and RB1‐null cancer cells express HMGA2.