Immunophenotypic, cytogenetic, gene expression, and mutational profiling of Sarc (sarcoma) cells. (A) Morphology (hematoxylin and eosin stain) and immunohistologically detected expression of markers indicative of muscle differentiation (myogenin and desmin). Proliferative rate of the tumor was determined by expression of Ki-67. (B) Clonal rearrangement of immunoglobulin heavy chain (IGH) detected in primary (p) and cultured (c) Sarc cells matching the clonal IGH peak present in the control MCL-E cells. (C) IGH-CCND1 gene fusion (yellowish spots pointed to by arrows) detected in Sarc cells by fluorescence in situ hybridization (FISH). (D) Expression of genes associated with mature B-cell differentiation stage by the depicted cell populations identified by the genomic-scale RNA-Seq analysis. (E) Expression of genes associated with striated muscle (upper) or neuronal (lower) differentiation in the same cell populations detected also by RNA-Seq. (F) Whole-exome sequencing-identified nonsense mutation of RB1 gene confirmed in Sarc cells by pyrosequencing. (G) Loss of expression of the RB1 protein by Sarc cells with MCL-RL cells⁴  serving as positive control. (H) Expression of the ENTPD8 and TP53 proteins by Sarc cells with MCL-RL cell line⁴  serving as positive control.