MPPE1 and cancer: Given that intratumoral cDC1 are also essential for T cell-based therapies in mouse tumor models (Broz et al., 2014, Salmon et al., 2016, Sánchez-Paulete et al., 2016, Spranger et al., 2015), our data further indicate that a low frequency of cDC1 might be one reason for the low response rate of cancer patients to immune checkpoint blockade.