MRC1 and Marinesco-Sjogren syndrome: Takayanagi et al. (2021) evaluated the expression of PD-L1 in samples collected from patients with NECC using IHC staining and found that 14 (56%) of 25 NECC samples were positive. Chen, L et al. (2021) used IHC to evaluate PD-L1 and MMR expression in 43 patients with SCNEC. Of the 43 patients, 22 (51%) had positive PD-L1 expression. All the patients were found to have MSS. Ji et al. (2021) performed IHC staining for assessment of PD-L1 and MMR expression on 20 NECC specimens.