Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of PDCD1/PD-1, thereby regulating T-cells-mediated immunity (PubMed:30487606). Required for anti-tumor activity of T-cells by promoting the degradation of PDCD1/PD-1; the PDCD1-mediated inhibitory pathway being exploited by tumors to attenuate anti-tumor immunity and facilitate tumor survival (PubMed:30487606). May indirectly stimulate the activity of transcription factor KLF7, a regulator of neuronal differentiation, without promoting KLF7 ubiquitination (By similarity). . This is the function of FBXO38 (F-box protein 38, ENSG00000145868).