PSPC1 is a member of the Drosophila behaviour/human splicing protein family (DBHS), which were previously found to have a role in DNA repair, however its precise function in the DNA damage response was unclear. To further understand the role of PSPC1 in response to DNA damage, we silenced PSPC1 and treated cells with several DNA damaging agents including cisplatin, mitomycin C (MMC), hydroxyurea (HU), olaparib and irradiation. Interestingly, we observed that silencing PSPC1 promoted sensitivity to DNA interstrand crosslinking agents such as cisplatin and MMC but not the remaining DNA damaging agents. Given that cells with deficiency in the Fanconi Anaemia (FA) pathway are also sensitive to DNA interstrand crosslinking agents, we next investigated the role of PSPC1 in the FA pathway. Our results demonstrate for the first time that activation and mono-ubiquitination of FANCD2 was significantly reduced, upon MMC treatment in PSPC1-depleted cells. In addition, the expression of RPA32, FANCD2 and ATR were significantly reduced in PSPC1 knockout cells. Significantly, following RNA sequencing of the PSPC1 KO cells, expression of a large proportion of the FA core complex and FA-associated proteins (FAAPs) were reduced at the RNA level. Moreover, our data showed increased levels of DNA damage was induced and the repair of MMC-induced DNA damage was delayed upon PSPC1 loss. Taken together, our results suggest that PSPC1 is required to activate FANCD2-mediated DNA repair upon treatment with DNA interstrand crosslinking agents. Our results also suggest that loss of PSPC1 is a biomarker of sensitivity to DNA interstrand crosslinking agents. Given that PSPC1 loss is a feature of many tumour types, our data suggests that screening patient tumours for PSPC1 expression may represent an important biomarker for therapeutic selection.