MKI67 and melanoma: In this regard, sections from explanted melanomas which developed after injection of melanoma cells together with GCP‐2 silenced replicative senescent fibroblasts into SCID mice showed completely suppressed CREB activation (Figure 4C, bottom middle panel) with reduced expression of the proliferation marker Ki67 (Figure S13A, outer right upper row, bottom panel, and Figure S13B) and enhanced expression of the apoptosis marker caspase 3 in melanoma cells (Figure S13A, lower row, outer right bottom panel, and Figure S13C).