IHC has been able to elucidate many prognostic and predictive biomarkers including MART1/Ki-67, preferentially expressed antigen of melanoma (PRAME), makers of lymphovascular invasion (e.g., CD31/SOX-10) and mismatch repair (MMR) proteins, among many others (Torres-Cabala et al., 2020). The gene discussed is MKI67; the disease is melanoma.