MWCL-1 cells retain both copies of chromosome 6q but exhibit monoallelic expression of mutated TP53. (A) Representative FISH image of MWCL-1 cells at a 12-month passage confirming the absence of a 6q deletion. Two hybridization signals are observed for both the probe specific to the centromere of chromosome 6 (green signal), and the locus-specific, c-MYB probe (red signal). (B) Representative FISH image of MWCL-1 cells at a 12-month passage demonstrating monoallelic loss of TP53. Two hybridization signals are observed for the probe specific to chromosome 17 (green signal), but only one signal is observed for the locus-specific, TP53 probe (red signal).