Monooxygenase that promotes depolymerization of F-actin by mediating oxidation of specific methionine residues on actin to form methionine-sulfoxide, resulting in actin filament disassembly and preventing repolymerization (PubMed:29343822). In the absence of actin, it also functions as a NADPH oxidase producing H(2)O(2) (PubMed:21864500, PubMed:26845023, PubMed:29343822). Acts as a cytoskeletal regulator that connects NEDD9 to intermediate filaments. Also acts as a negative regulator of apoptosis via its interaction with STK38 and STK38L; acts by antagonizing STK38 and STK38L activation by MST1/STK4. Involved in regulation of lamina-specific connectivity in the nervous system such as the development of lamina-restricted hippocampal connections. Through redox regulation of the actin cytoskeleton controls the intracellular distribution of secretory vesicles containing L1/neurofascin/NgCAM family proteins in neurons, thereby regulating their cell surface levels (By similarity). May act as Rab effector protein and play a role in vesicle trafficking. H(+) + L-methionyl-[F-actin] + NADPH + O2 = H2O + L-methionyl-(R)-S-oxide-[F-actin] + NADP(+) H(+) + NADPH + O2 = H2O2 + NADP(+) kcat is 0.28 sec(-1) for NADPH for the NADPH oxidase reaction. Interacts with STK38 and STK38L (By similarity). Interacts with RAB1B, RAB8A, RAB10, RAB13 and RAB15 (in their GTP-bound forms); binding to RAB1B is of low affinity compared to other Rab proteins; at least in case of RAB8A and RAB10 can bind 2 molecules of the Rab proteins simultaneously; ternary complex formation of RAB8A, RAB13 and MICAL1 is possible. Associates with the SH3 domain of NEDD9. Interacts with VIM and PLXNA3. Interacts with RAB1B. Accumulates transiently at the abscission site before abscission occurs. Expressed in the thymus, lung, spleen, kidney, testis and hematopoietic cells. The bivalent Mical/EHBP Rab binding (bMERB) domain, mediates binding to predominantly Rab8, Rab10, Rab10, Rab13 and Rab15 (in their GTP-bound forms). The C-terminal coiled coil part contains the plexin-interacting region. Belongs to the Mical family. The reaction mechanism is subject to discussion. Some work suggest MICAL enzymes directly oxidize actin methionine residues to produce methionine-(R)-S-oxide. Other publications suggest that the enzyme functions as a NADPH oxidase producing H(2)O(2) (EC 1.6.3.1) and that it is the produced H(2)O(2) that is responsible for the methionine-(R)-S-oxide production.