CD274 and melanoma: To this end, flow cytometric analysis showed that HSPCs (or LSK cells; lineage (Lin)−Sca1+cKit+) express PD-L1 at steady state and its expression was not altered after B16.F10 melanoma cell inoculation (Figure 2A), whereas it was significantly increased upon inoculation with immunogenic MB49 bladder cancer cells (Figure 2B).