During interphase, required for microtubule organizing and anchoring activities. During mitosis, required for the organization and stabilization of the spindle pole (PubMed:28394342). Isoform 2/alpha is particularly important for the regulation of microtubule anchoring, microtubule stability, spindle architecture and spindle orientation, compared to isoform 1/beta (PubMed:28394342). May promote cell cycle arrest by enhancing the inhibition of CDK2 activity by CDKN1A. May be required for repair of DNA damage by homologous recombination in conjunction with BRCA2. May not be involved in non-homologous end joining (NHEJ). Interacts with BRCA2, CDKN1A and MTDH/LYRIC (PubMed:10878006, PubMed:11313963, PubMed:14726710, PubMed:15713648, PubMed:18440304). Isoform 2/alpha, but not isoform 1/beta, interacts with DCTN1/p150-glued and ACTR1A/ARP1 (PubMed:28394342). Both isoform 1 and isoform 2 interact with alpha-, beta- and gamma-tubulins (PubMed:28394342). Interacts with TENT5C; the interaction has no effect on TENT5C poly(A) polymerase function (PubMed:28931820). Colocalizes with BRCA2 in discrete nuclear foci (PubMed:15713648). In interphase, preferential localizes to the mother centriole (PubMed:28394342). Recruited to the spindle pole matrix and centrosome by microtubules and dynein/dynactin activity (PubMed:28394342). Isoform 1/beta tends to be less abundant at, and less strongly associated with, centrosomes than isoform 2/alpha. Isoform 2/alpha tends to be more abundant at, and more strongly associated with, centrosomes than isoform 1/beta. Expressed at high levels in testis and skeletal muscle and at lower levels in brain, heart, kidney, liver, lung, ovary, pancreas, placenta, and spleen. Isoform 1 is expressed throughout the cell cycle. Isoform 2 is expressed following mitosis and peaks in the G1/S phase of the cell cycle. HT1080 cells that constitutively express low levels of BCCIP display increased levels of spontaneous single-stranded DNA and double-strand breaks. Belongs to the BCP1 family.